Issue Vol. 10, 04 2012

July/August Issue, 2012
ATM Letters July/August Issue, 2012
ATM Letters Journal
Super Moon? How About a Super Sun! On May 5, 2012, while everyone else was waiting for the Super Moon astrophotographer Alan Friedman was out capturing this super image of a super Sun from his back yard in Buffalo, NY! Taken with a specialized telescope that can image the Sun in hydrogen alpha light, Alans photo shows the intricate detail of our home stars chromosphere - the layer just above its surface, or photosphere. Prominences can be seen rising up from the Suns limb in several places, and long filaments - magnetically-suspended lines of plasma - arch across its face. The fuzzy texture is caused by smaller features called spicules and fibrils, which are short-lived spikes of magnetic fields that rapidly rise up from the surface of the Sun. On the left side it appears that a prominence may have had just detached from the Suns limb, as theres a faint cloud of material suspended there. Credit: Alan Friedman/UT
ATM Letters Journal
Amazing Astrophoto: The Phases of Venus. Wow! Take a look at how Venus has changed in the night sky the past five months! The Planet Venus, The Roman goddess of love and beauty and the closest planet to us - especially now just as it gets closest - will transit across the Sun soon, said astrophotographer Efrain Morales. This sequence is a five month transition showing its size continuing to grow and its crescent getting thinner as time progresses. Credit: Efrain Morales/UT
ATM Letters Journal
Stunning Astrophoto: Auroral Explosion of Color. This gorgeous and unusual aurora display was captured by Brendan Alexander from the North Coast of Donegal, Ireland. We were treated to an absolutely stunning aurora display on the morning of the 24th of April 2012, Brendan wrote on UT Flickr page. Easily the best I have seen in my eventful four years of sky watching. The display started off strong at nightfall (22:00 UT) with intense and almost static rays. However shortly after magnetic midnight the aurora came to life, complete with waving curtains, shimmering rays, vivid colours and pulsating heart. A spellbinding and enrolling time was endured from dusk to dawn. A Stunning display to remember during the bright summer months ahead. Brendan used a Canon 1000D camera with a Sigma 20mm F1.8 lens. Exposure: 8 11 sec ISO 1600. Credit: Brendan Alexander/UT
CONTENTS
RoboScopes - Real Armchair Astronomy 14 SPECTRUM
Robotic telescopes can be fun, they can lead to amazing things
Issue July/August | Volume 10 | Number 4
Vertical Direct North/South Sundial

A Sundial primer
23 Troughton & Simms Dividet-Lens Double Image Micrometer

Optical analysis
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PRAXIS
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Orbital Mechanics 40
Study of the motions of artificial satellites and space vehicles
BACK TO THEORY
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Globular Cluster and Cyber Sky

Simulation globular clusters and sky pictorially
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ASTRONOMICAL COMPUTING
MODAS NG Update Mirror Testing

Foucault test, Ronchigrams mirror real profile
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COMPUTER AND TELESCOPES
History Andrew Ainslie Common: The Common Man

Andrew Ainslie Common (1841-1903) was a pioneer in the construction of large silvered mirror telescopes. He showed the potential of such instruments to photograph the heavens provided they were accurately driven and situated in a suitable observing location. Two of his telescopes are still in operation today, the 36-inch Crossley reflector at the Lick Observatory in Calfifornia and the 60-inch Rockefeller reflector at the Boyden Observatory, Bloemfontein, South Africa...
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BIBLIOGRAPHY
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See also
RESOURCES EDITOR NOTES NEWS BOOKS GALLERY 6 09 69 123 149 158 163
ON THE COVER
Contents
ADVERISEMENTS NEXT ISSUE
ATMLJ 10 Anniversary Looking back Moving Forward

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Credit: Pencho Markishki
Copyright Information We believe that most of the texts and images are in the public domain. We do not own the copyright to the texts and images used in ATM Letters Journal. We have not kept a record of where we found any of the texts and images we have used. If you believe that you own the rights to any of the texts and images we use, please contact us and we will add an acknowledgement. All logos and trademarks in ATM Letters Journal are property of their respective owner. Universe Today allows reprinting of all his stories, when a credit says that original story was originally published on Universe Today.
Issue Resources
Examples
sw_win_moonphase.zip sw_xls_vertdial.zip
Moon phase by Ivan Krastev (3x - Desktop, small and large Widget) Vertical Direct North/South sundial by Carl Sabanski (Excel sheet)
Tools
gift_moonphasewgl.zip Large Moon Phase widget by Ivan Krastev

2549158 2576011 2520636 2520635 2520633 Wide-Angle Eypiece Lens System Catadioptric Optical System Optical Objective Optical System Optical System (PDF) (PDF) (PDF) (PDF) (PDF)
e-Articles, e-Books us_patents.zip - Patent, - Patent, - Patent, - Patent, - Patent, ebooks.zip
- Eng, Antiquarian - Astronomy - New and Original Theories of the Great (EPUB) Physical Forces - Rogers, Henry Raymond - Eng, Antiquarian - Astronomy - Side-lights on Astronomy and Kindred Fields(EPUB) of Popular Science - Newcomb, Simon - Eng, Antiquarian - Astronomy - Recreations in Astronomy - Warren, Henry (EPUB) - Eng, Antiquarian - Optics - Light waves and their uses - A. A. Michelson (DJVU)
Enjoy!
For new Readers
What is the ATM Letters? This is electronic based Journal (100% recycling) Available in Adobe PDF (in the feature like free iBook from the Apple Store) It comes out in the feature 3 times in year (the commercial release was available bi-monthly). Cover Page This is the journals title page, includes journal logo, issue label, big format picture and list of issues highlights. This page is followed often by three additional pages with some amazing amateur astrophotography images. Contents This is the issues columns summary with paging. Also thumbnail screen shots and very short description will be given. This page is followed by page with sort description of the issues resources like freeware ATM software written by the editor or other ATM, different tools, electronically articles and free e-books. Editor Notes Here is the editors place for short announcements. Letters to the Editor Here is the place, where the reader can report shortly all related to telescope making, interesting links, journal opinion, notice about present issues or articles, short information or interesting notices. Up to two sites are reserved Small ATM Companies Here I reserved place for your ATM Group, Association, Observatory or small Company, where you can tell in brief to other ATM about your establishing, experience, interest, works, friends, telescopes and meetings. Photos are welcomed. Up to two sites are reserved.
What you will find in ATM Letters? Which are the journal columns?
Glossary Here is the place for shortly and easy described optics key words, for examples aberration types, sign conventions, types of optical surfaces, kind of telescopes etc. Diagrams and pictures will be included. The next four columns are the most impressive journal sections: Praxis This column allows you make public to other reader your own built telescope, experience in design, constructing, making, grinding, polishing, testing etc. Pictures, schemes and graphics are highly recommended. Back to Theory Here is the Treasure Island for all advanced ATM. Any article will include all formulas needed to perform own design and analysis of your telescope. Here will be reviewed in details any telescope system used by the amateur astronomers and professionals, design of eyepieces, field correctors, mirror testing, baffling and collimating etc. Also this section will be edited in connections with the next column, where in the same or the next issue will appear full working program written in different programming languages. Astronomical, Numerical and Optical Computing This is the programmer corner, maybe the most practical column, which includes useful telescope designs, analyses and testing BASIC programs suggested by readers or written by me. All programs will be here (or in the column Back to Theory) theoretical explained. I will write you additional the same programs also in pascal, java (applets), java and html scripts (calculators), which you can use free in your home page. MS-Excel fans will be supplied with a lot of spreadsheets. Here is also place to introduce you in easy way in some numerical methods, used by the amateurs, like interpolation (needed by curve fitting), integration (needed for calculation of wave aberration), 3D graphic plotting etc. Astronomical calculations will be discussed too.
For new Readers
Computer and Telescopes This column will report you all about existing telescope design, analysis and mirror testing packages, description, program features, mastering of the programs, design file formats, useful types & tricks, discussing useful designs. This column has two major sub columns called: Software Overview and Test Report. All Discussed designs, will be tested with different packages (for example MODAS, ZEMAX, OSLO, OpTaliX, ATMOS etc.) and the results finally compared. News This column will inform you about new books publication, new software releases, and latest news from space, astronomy, and new technologies. A part of this column is the Eyes of the World, Telescope Review, and Scientific Instruments (both antiques and modern). Bibliography Here you will find quantity bibliographic data about history of optics, telescopes, telescope making, astronomy, famous optician and astronomers, old observatories, antique telescopes, books and magazines bibliography etc. This column has three major sub columns called Pioneers in Optics, Rambling through the Years and A Brief History
Editor Notes
ATMLJ 10th Anniversary - Looking Back, Moving Forward

Dear ATMLJ reader! Dear Friends! Looking Back Ten years ago, in one hot August summers day of 2003, I decided the beginning editing of my own Journal for amateur astronomers and telescope makers, focused on telescope making, telescope design and optics in general, astronomical, optical and numerical computing, history of telescopes, optics and astronomy in general and many other related stuff. At that time I have had not any idea, how long I will be available to make this job (today too ). After my first successful project MODAS this was my second project but with one difference - without any experience in this area. The first problem with my Journal was the name that I choose - ATM Journal. Not only at this time, but later and today too, was not available any other journal with such name. A few weeks after the promotion of my journal, I received via email, the first statement - I can't use the name ATM Journal because it is copyright owned by Bill Cook, former editor of not more existing ATM Journal. So I had chosen the name ATM Letters Journal or as you known today as ATMLJ. All this was not new for me, a few years before, similar people from the ATM community tried to do the similar things with my MODAS. Also the moving forward is often not problem-free. The copyright will be our great problem in the feature, in any kind, for any from us in our daily living. This is one of the reasons to release my journal free for a few years beginning with this anniversary issue (see below). Regarding to the copyright, a joke that I read a few weeks (Projects ACTA/PIPA/SOPA):
"Conversation between two friends, who says one to the other: - I gotta tell you, I have a huge problem with my company logo. - Why? - Because it is round like these by Pepsi..."
In the first issue of ATMLJ I defined the columns that I will edit in the feature and some names was changed with the years. I think that with the time, progressed too the face (layout) of ATMLJ. From begin I choose column's layout with two rows, looking very professional (similar to those from Applied Optics Journal and JOSA). Many readers say that the printing issue looks great. Other says, they have shifted to ATMLJ after they cannot find more interesting stuff in Sky & Telescope and Astronomy magazines. Or other what I can say is that about 75% from all readers are subscriber since August 2003!
Editor Notes
Thank you for the faithful and the good words all these years! Nevertheless, I know that many things could be made better in ATMLJ and this will be my task in the feature. My great wish is more and more amateurs to submit his articles. Maybe this will happen next year (2013), were ATMLJ is free. I have a large database on amateurs (over 1000) interested on ATMLJ, and Im sure all will enjoy the magazine. But maybe the reason for the low activity of the amateur astronomers is the hard time were we living, many of us has many problems than enjoying his hobby. The possibility to buy a telescope in a supermarket (China made it possible) has negative effects on the offspring of young amateur astronomers and telescope makers. If you look to the most popular atm forums, a great part from the community is in the age between 40 and 60. The same is also true for the owner of the available home pages of active ATM. What a pity! Maybe it is unknown for the readers that ATMLJ was always free for many amateur astronomers and telescope makers around the world, people that have had not the possibility to pay by one or other reason, but people that love his hobby. For me was great pleasure to help on such people with free subscription! I hope we can look back again in 10 years! I'm sure! Moving Forward Maybe some of you have felt it, that in the past and this year, I'm tired. Often I could not complete the issue ready in a time. Actually, the tiredness is not only one reason. My biggest problem is that in the last 10 years I have to work 6 days weekly. So I have to recover me only on Sunday. But if a task is a fun, you do not feel the tiredness, not at the beginning. My free time is very limited for so many things I wish do. I decided in the feature for a while to reduce the number of issues to 2-3 yearly (spring, summer and Christmas). Of course I will try to put the stuff from 6 issues in these two or three issues. All issues will be available for free and you will receive still notification, when a new issue is available. Of course reader currently subscribed for 2013 will receive his money back. The difference from earlier is that I'm not under the pressure that issue is not completed in a time and I will have additional time for other projects. In this year I discovered again the fun by free programming (programming something when I have time and inclination for that) and I wish support you with many new free programs and tools related to the astronomy, optics and science in general for both Windows, Mac OS X and iOS platforms. Beginning with this anniversary issue you can enjoy a lot of tools that I programmed especially for the ATMLJ readers. In the next year I will spend my free time for finishing the development of my MODAS NG. But here is one restriction related to the license. In the next few years will be not available commercial version of MODAS NG. Of course the users that currently ordered MODAS NG ATM will receive regular update until the development is finished. Don't worry, MODAS will be available for this period as freeware version with limitation on used surfaces number and working like demo version over this limitation. The free release of MODAS NG and the magazine has some personal backgrounds too (unfortunately again problems with my ex-wife) and the problem should no more exists in few years.
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Editor Notes
Additional to my MODAS and ATMLJ, I wish to start two other projects (very, very old wish from me): 1. Writing of optical design book "Astronomical Optics" in conjunction with MODAS NG as a tool in main focus and history of telescopes and their builder and history of optics in general too. Of course here exist many similar books about this stuff, but I have some other ideas that not occur in any from them. 2. Start new project called "The Human of Dawn" related to Archaeology, Paleontology and Alternative History and History in general. This project will have own home page and will include the development of software tools with the same name and will allows professionals and amateurs interested in this area to analyze great amount of data and evidences with scientific methods and art given never before. Such tools should be great help for all that look deep back into our origin and search answers of questions like Who are we?, Where we come from?, Where are we going?. All these evidences are there in front of our eyes, one only has to look right. Did you know that over 20 000 000 prehistoric drawings on rocks and in caves around the world exist, and only a fraction of it has been explored or the ortodox archaeology wish not to be explored? And each drawing can tell us a story! I hope that what I am doing now is not a step back, but moving forward! Best regards Ivan Austria, Moedling, 22 August 2012
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Editor Notes
ATMLJ 10 Anniversary Gift Beautiful Large Moon Phase Widget
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Enjoy!
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Spectrum - RoboScopes - Real Armchair Astronomy
Using and getting the most out of robotic astronomy Whilst nothing in the field of amateur astronomy beats the feeling of being outside looking up at the stars, the inclement weather many of us have to face at various times of year, combined with the task of setting up and then packing away equipment on a nightly basis, can be a drag. Those of us fortunate enough to have observatories dont face that latter issue, but still face the weather and usually the limits of our own equipment and skies. Another option to consider is using a robotic telescope. From the comfort of your home you can make incredible observations, take outstanding astrophotos, and even make key contributions to science! The main elements which make robotic telescopes appealing to many amateur astronomers are based around 3 factors. The first is that usually, the equipment being offered is generally vastly superior to that which the amateur has in their home observatory. Many of the robotic commercial telescope systems, have large format mono CCD cameras, connected to high precision computer controlled mounts, with superb optics on top, typically these setups start in the $20-$30,000 price bracket and can run up in to the millions of dollars. Combined with usually well defined and fluid workflow processes which guide even a novice user through the use of the scope and then acquisition of images, automatically handling such things as dark and flat fields, makes it a much easier learning curve for many as well, with many of the scopes specifically geared for early grade school students.
Spectrum
The second factor is geographic location. Many of the robotic sites are located in places where average rainfall is a lot lower than say somewhere like the UK or North Eastern United States for example, with places like New Mexico and Chile in
Top/Bottom: The Faulkes Telescope North/South. The two Faulkes Telescopes have now been incorporated into the even grander scheme of the Las Cumbres Observatory Global Telescope Network (LCOGT.net). Established by Wayne Rosing, ex-vice president of software engineering at Google, this project will see more than 30 additional telescopes constructed around the world ranging in size from 40cm to 1m and made available to schools from all countries for educational purposes. Credit: Faulkes Telescope/LCOGT
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RoboScopes - Real Armchair Astronomy
The LT's primary mirror undergoing final cleaning by ING staff (Juerg Rey at right), before being transferred into the WHT's coating unit on La Palma. Credit: Liverpool Telescope/A. Scott
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The Liverpool Telescope as seen from the window of the Mercator Telescope's kitchen. Credit: Liverpool Telescope/J. Marchant
Spectrum
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The Liverpool Telescope. Credit: Liverpool Telescope/R. Smith
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particular offering almost completely clear dry skies year round. Robotic scopes tend to see more sky than most amateur setups, and as they are being controlled over the Internet, you yourself dont even have to get cold outside in the depths of winter. The beauty of the geographic location aspect is that in some cases, you can do your astronomy during the daytime, as the scopes may be on the other side of the world. The third is ease of use, as its nothing more than a reasonably decent laptop, and solid broadband connection thats required. The only thing you need worry about is your internet connection dropping, not your equipment failing to work. With scopes like the Faulkes or Liverpool Telescopes, ones I use a lot, they can be controlled from something as modest as a netbook or even an Android/iPad/iPhone, easily. The issues with CPU horsepower usually comes down to the image processing after you have taken your pictures. Software applications like the brilliant Maxim DL by Diffraction Limited which is commonly used for image post processing in amateur and even professional astronomy, handles the FITS file data which robotic scopes will deliver. This is commonly the format images are saved in with professional observatories, and the same applies with many home amateur setups and robotic telescopes. This software requires a reasonably fast PC to work efficiently, as does the other stalwart of the imaging community, Adobe Photoshop. There are some superb and free applications which can be used instead of these two bastions of the imaging fraternity, like the excellent Deep Sky stacker, and IRIS, along with the interestingly named GIMP which is variant on the Photoshop theme, but free to use. Some people may say just handling image data or a telescope over the internet detracts from real astronomy, but its how professional astronomers work day in day out, usually just doing data reduction from telescopes located on the other side of the world. Professionals can wait years to get telescope time, and even then rather than actually being a part of the imaging process, will submit imaging runs to observatories, and wait for the data to roll in. (If anyone wants to argue this factjust say Try doing eyepiece astronomy with the Hubble) The process of using and imaging with a robotic telescope still requires a level of skill and dedication to guarantee a good night of observing, be it for pretty pictures or real science or both. Location Location Location The location for a robotic telescope is critical as if you want to image some of the wonders of the Southern Hemisphere, which those of us in the UK
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Top: A look at the Faulkes Telescope South inside. Middle: Screenshot of the Faulkes Telescope realtime interface. Bottom: iTelescope systems are located all over the globe. Credit: Faulkes Telescope/LCOGTiTelescope project
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or North America will never see from home, then youll need to pick a suitably located scope. Time of day is also important for access, unless the scope system allows an offline queue management approach, whereby you schedule it to do your observations for you and just wait for the results. Some telescopes utilise a real time interface, where you literally control the scope live from your computer, typically through a web browser interface. So depending on where in the world it is, you may be in work, or it may be at a very unhealthy hour in the night before you can access your telescope, its worth considering this when you decide which robotic system you wish to be a part of. Telescopes like the twin Faulkes 2-metre scopes, which are based on the Hawaiian island of Maui, atop a mountain, and Siding Spring, Australia, next to the world famous Anglo Australian Observatory, operate during usual school hours in the UK, which means night time in the locations where the scopes live. This is perfect for children in western Europe who wish to use research grade professional technology from the classroom, though the Faulkes scopes are also used by schools and researchers in Hawaii. The type of scope/camera you choose to use, will ultimately also determine what it is you image. Some robotic scopes are configured with wide field large format CCDs connected to fast, low focal ratio telescopes. These are perfect for creating large sky vistas encompassing nebulae and larger galaxies like Messier 31 in Andromeda. For imaging competitions like the Astronomy Photographer of the Year competition, these wide field scopes are perfect for the beautiful skyscapes they can create. Scopes like the Faulkes Telescope North, even though it has a huge 2m (almost the same size as the one on the Hubble Space Telescope) mirror, is configured for smaller fields of view, literally only around 10 arcminutes, which will nicely fit in objects like Messier 51, the Whirpool Galaxy, but would take many separate images to image something like the full Moon (If Faulkes North were set up for that, which its not). Its advantage is aperture size and immense CCD sensitivity. Typically our team using them is able to image a magnitude +23 moving object (comet or asteroid) in under a minute using a red filter too! A field of view with a scope like the twin Faulkes scopes, which are owned and operated byLCOGT is perfect for smaller deep sky objects and my own interests which are comets and asteroids.Many other research projects such as exoplanets and the study of variable stars are conducted using these telescopes.Many schools start out imaging
Global Rent-A-Scope interface
nebulae, smaller galaxies and globular clusters, with our aim at the Faulkes Telescope Project office, to quickly get students moving on to more science based work, whilst keeping it fun. For imagers, mosaic approaches are possible to create larger fields, but this obviously will take up more imaging and telescope slew time. Each robotic system has its own set of learning curves, and each can suffer from technical or weather related difficulties, like any complex piece of machinery or electronic system. Knowing a bit about the imaging process to begin with, sitting in on others observing sessions on things like Slooh, all helps. Also make sure you know your target field of view/size on the sky (usually in either right ascension and declination) or some systems have a guided tour mode with named objects, and make sure you can be ready to move the scope to it as quickly as possible, to get imaging. With the commercial robotic scopes, time really is money. Magazines like Astronomy Now in the UK, as well as Astronomy and Sky and Telescope in the United States and Australia are excellent resources for finding out more, as they regularly feature robotic imaging and scopes in their articles. Online forums like cloudynights.com and stargazerslounge.com also have thousands of active members, many of whom regularly use robotic scopes and can give advice on imaging and use, and there are dedicated groups for robotic astronomy like the Online Astronomical Society. Search engines will also give useful information on what is available as well. To get access to them, most of the robotic scopes require a simple sign up process, and then the user can either have limited free access, which is usually an introductory offer, or just start to pay for time. The scopes come in various sizes and quality of camera, the better they are, usually the more you pay. For education and school users as well
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as astronomical societies, The Faulkes Telescope (for schools) and the Bradford Robotic scope both offer free access, as does the NASA funded Micro Observatory project. Commercial ones like iTelescope, Slooh and Lightbuckets provide a range of telescopes and imaging options, with a wide variety of price models from casual to research grade instrumentation and facilities. So what about my own use of Robotic Telescopes? Personally I use mainly the Faulkes North and South scopes, as well as the Liverpool La Palma Telescope. I have worked with the Faulkes Telescope Project team now for a few years, and its a real honour to have such access to research grade intrumentation. Our team also use the iTelescope network when objects are difficult to obtain using the Faulkes or Liverpool scopes, though with smaller apertures, were more limited in our target choice when it comes to very faint asteroid or comet type objects. After having been invited to meetings in an advisory capacity for Faulkes, late in 2011 I was appointed pro am program manager, co-ordinating projects with amateurs and other research groups. With regards to public outreach I have presented my work at conferences and public outreach events for Faulkes and were about to embark on a new and exciting project with the European Space Agency whom I work for also as a science writer. My use of Faulkes and the Liverpool scopes is primarily for comet recovery, measurement (dust/coma photometry and embarking on spectroscopy) and detection work, those icy solar system interlopers being my key interest. In this area, I co-discovered Comet C2007/Q3 splitting in 2010, and worked closely with the amateur observing program managed by NASA for comet 103P, where my images were featured in National Geographic, The Times, BBC Television and also used by NASA at their press conference for the 103P pre-encounter event at JPL. The 2m mirrors have huge light grasp, and can reach very faint magnitudes in very little time. When attempting to find new comets or recover orbits on existing ones, being able to image a moving target at magnitude 23 in under 30s is a real boon. I am also fortunate to work alongside two exceptional people in Italy, Giovanni Sostero and Ernesto Guido, and we maintain a blog of our work, and I am a part of the CARA research group working on comet coma and dust measurements, with our work in professional research papers such as the Astrophysical Journal Letters and Icarus. The Imaging Process When taking the image itself, the process starts really before you have access to the scope. Knowing the field of view, what it is you want to achieve is critical, as is knowing the capabilities of ATM July/August 2012 in question, and theLetters scope and Issue, camera importantly, whether or not the object you want to image is visible from the location/time youll be Knowing the field of view, what it is you want to achieve is critical, as is knowing the capabilities of the scope and camera in question, and importantly, whether or not the object you want to image is visible from the location/time youll be using it. First thing I would do if starting out again is look through the archives of the telescope, which are usually freely available, and see what others have imaged, how they have imaged in terms of filters, exposure times etc, and then match that against your own targets. Ideally, given that in many cases, time will be costly, make sure that if youre aiming for a faint deep sky object with tenuous nebulosity, you dont pick a night with a bright Moon in the sky, even with narrowband filters, this can hamper the final image quality, and that your choice of scope/camera will in fact image what you want it to. Remember that others may also want to use the same telescopes, so plan ahead and book early. When the Moon is bright, many of the commercial robotic scope vendors offer discounted rates, which is great if youre imaging something like globular clusters maybe, which arent as affected by the moonlight (as say a nebula would be) Forward planning is usually essential, knowing that your object is visible and not too close to any horizon limits which the scope may impose, ideally picking objects as high up as possible, or rising to give you plenty of imaging time. Once thats all done, then following the scopes imaging process depends on which one you choose, but with something like Faulkes, its as simple as selecting the target/FOV, slewing the scope, setting the filter, and then exposure time and then waiting for the image to come in. The number of shots taken depends on the time you have. Usually when imaging a comet using Faulkes I will try to take between 10 and 15 images to detect the motion, and give me enough good signal for the scientific data reduction which follows. Always remember though, that youre usually working with vastly superior equipment than you have at home, and the time it takes to image an object using your home setup will be a lot less with a 2m telescope. A good example is that a full colour high resolution image of something like the Eagle Nebula can be obtained in a matter of minutes on Faulkes, in narrowband, something which would usually take hours on a typical backyard telescope. For imaging a non moving target, the more shots in full colour or with your chosen filter (Hydrogen Alpha being a commonly used one with Faulkes for nebula) you can get the better. When imaging in
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colour, the three filters on the telescope itself are grouped into an RGB set, so you dont need to set up each colour band. Id usually add a luminance layer with H-Alpha if its an emission nebula, or maybe a few more red images if its not for luminance. Once the imaging run is complete, the data is usually placed on a server for you to collect, and then after downloading the FITS files, combine the images using Maxim (or other suitable software) and then on in to something like Photoshop to make the final colour image. The more images you take, the better the quality of the signal against the background noise, and hence a smoother and more polished final shot. Between shots the only thing that will usually change will be filters, unless tracking a moving target, and possibly the exposure time, as some filters take less time to get the requisite amount of light. For example with a H-Alpha/OIII/SII image, you typically image for a lot longer with SII as the emission with many objects is weaker in this band, whereas many deep sky nebula emit strongly in the H-Alpha. The Image Itself As with any imaging of deep sky objects, dont be afraid to throw away poor quality sub frames (the shorter exposures which go to make up the final long exposure when stacked). These could be affected by cloud, satellite trails or any number of factors, such as the autoguider on the telescope not working correctly. Keep the good shots, and use those to get as good a RAW stacked data frame as you can. Then its all down to post processing tools in products like Maxim/Photoshop/Gimp, where youd adjust the colours, levels, curves and possibly use plug ins to sharpen up the focus, or reduce noise. If its pure science your interested in, youll probably skip most of those steps and just want good, calibrated image data (dark and flat field subtracted as well as bias) The processing side is very important when taking shots for aesthetic value, it seems obvious, but many people can overdo it with image processing, lessening the impact and/or value of the original data. Usually most amateur imagers spend more time on processing than actual imaging, but this does vary, it can be from hours to literally days doing tweaks. Typically when processing an image taken robotically, the dark and flat field calibration are done. First thing I do is access the datasets as FITS files, and bring those in to Maxim DL. Here I will combine and adjust the histogram on the image, possible running multiple iterations of a deconvolution algorithm if the start points are not as tight (maybe due to seeing issues that night). Once the images are tightened up and then stretchATM Letters July/August Issue, 2012
ed, I will save them out as FITS files, and using the free FITS Liberator application bring them in to Photoshop. Here, additional noise reduction and contrast/level and curve adjustments will be made on each channel, running a set of actions known as Noels actions (a suite of superb actions by Noel Carboni, one of the worlds foremost imaging experts) can also enhance the final individual red green and blue channels (and the combined colour one). Then, I will composite the images using layers into a colour final shot, adjusting this for colour balance and contrast. Possibly running a focus enhancement plug in and further noise reduction. Then publish them via flickr/facebook/twitter and/or submit to magazines/journals or scientific research papers depending on the final aim/goals. Serendipity can be a wonderful thing I got in to this quite by accident myself. In March 2010, I had seen a posting on a newsgroup that Comet C/2007 Q3, a magnitude 12-14 object at the time, was passing near to a galaxy, and would make an interesting wide field side by side shot. That weekend, using my own observatory, I imaged the comet over several nights, and noticed a distinct change in the tail and brightness of the comet over two nights in particular. A member of the BAA (British Astronomical Association), seeing my images, then asked if I would submit them for publication. I decided however to investigate this brightening a bit further, and as I had access to the Faulkes that week, decided to point the 2m scope at this comet, to see if anything unusual was taking place. The first images came in, and I immediately, after loading them in to Maxim DL and adjusting the histogram, noticed that a small fuzzy blob appeared to be tracking the comets movement just behind it. I measured the separation as only a few arcseconds, and after staring at it for a few minutes, decided that it may have fragmented. I contacted Faulkes Telescope control, who put me in touch with the BAA comet section director, who kindly logged this observation the same day. I then contacted Astronomy Now magazine, who leapt on the story and images and immediately went to press with it on their website. The following days the media furore was quite literally incredible. Interviews with national newspapers, BBC Radio, Coverage on the BBCs Sky at Night television show, Discovery Channel, Radio Hawaii, Ethiopia were just a few of the news/media outlets that picked up the story.. the news went global that an amateur had made a major astronomical discovery from his desk using a robotic scope. This then led on to me working with members of the AOP project with the NASA/University of Maryland EPOXI
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mission team on imaging and obtaining light curve data for comet 103P late in 2010, again which led to articles and images in National Geographic, The Times and even my images used by NASA in their press briefings, alongside images from the Hubble Space Telescope. Subscription requests to Faulkes Telescope Project as a result of my discoveries went up by hundreds of % from all over the world. In summary Robotic telescopes can be fun, they can lead to amazing things, this past year, a work experience student I was mentor for with the Faulkes Telescope Project, imaged several fields wed assigned to her, where our team then found dozens of new and un-catalogued asteroids, and she also managed to image a comet fragmenting. Taking pretty pictures is fun, but the buzz for me comes with the real scientific research I am now engaged in, and its a pathway I aim to stay on probably for the rest of my astronomical lifetime. For students and people who dont have the ability to either own a telescope due to financial or possibly location constraints, its a fantastic way to do real astronomy, using real equipment, and I hope, in reading this, youre encouraged to give these fantastic robotic telescopes a try.
NGC 6302 taken by Thomas Mills High School with the Faulkes Telescope
(Source: Universe Today/Nick Howes)
Comet C/2007 Q3 (Faulkes Telescope)
Credit: Nick Howes
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The LT open at sunset. Credit: Liverpool Telescope/A. Gomboc
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Praxis - Vertical Direct North/South Sundial by Carl Sabanski
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Definitions Vertical Sundial: any dial in which the dial plate is vertical. Latitude: is the angular position of a place north or south of the equator. Positive values in the Northern hemisphere, negative in the Southern hemisphere. Style Height/Style Angle (SH): of a polar style is the angle that the style makes with the sub-style line. Sub-Style (line): the line lying in the dial plane which is perpendicularly below (or behind for a vertical dial) the style. Hour Line: the line on a dial plate indicating the shadow position at a particular time (includes fractional as well as whole hours). Hour Angle (h, HA): the angle corresponding to the sun's position around its daily (apparent) orbit. Measured westward from local noon, it increases at a rate of 15 per hour. Thus 3 pm (Local Apparent Time) is 45 and 9 am is -45 Hour Line Angle (X, HLA): the angle that an hour line on a dial plate makes with the noon line. For a vertical dial, the angle increases counterclockwise. Azimuth (A, AZ): the angle of the sun, measured in the horizontal plane and from true south. Angles to the west are positive, those to east, negative. Thus due west is 90, north is 180, east is -90. The vertical sundial must be designed for the particular latitude () where it is to be used. The style height (SH) of gnomon is equal to the colatitude or 90 minus the latitude. The hour line angles (X, HLA) can be calculated as follows: X = arctan {cos * tan (h)} where h is the hour angle, in degrees, given by: h = (T24 - 12) * 15 and T24 is the time in 24-hour clock notation (hours after midnight) in decimal hours. The sun can only shine on a vertical direct south sundial in the Northern Hemisphere and a vertical direct north sundial in the Southern Hemisphere between 6 A.M. and 6 P.M. The sun will only shine on a vertical direct north sundial early in the morning and late in the afternoon. This will occur only in the spring and summer months and not at all in the fall and winter. The maximum number of hours that can be indicated on a vertical direct north sundial will occur on the summer solstice, June 20 or 21. In the morning this period will be from sunrise until the sun is due east and in the afternoon this period will be from when the sun is due west until sunset. "The Dialist's Companion" can be used to determine the periods of time that the sun shines on a direct north sundial. This program allows you to set any location, date and time. The image below shows that the program has been set for June 20, 2004 and the "Dial Time" is set to 12:00 pm. To accomplish this, the "Pinawa Central" time was entered as 12:00 pm and then the "End" key was selected to freeze the screen. As long as the "End" key is not selected again the "Pinawa Central" time can be adjusted to any time and the clock will remain frozen. Note that the time for "Solar Noon" is given as 12:25:12 pm. Entering this time will set the "Dial Time" to 12:00 pm. Note the following: The time for "Sunrise" is approximately 4:20 am. This is clock time. To get solar time or local apparent time, the "Total Correction" must be added. In this case the correction is approximately -25 minutes. Therefore, the earliest time of sunrise is 3:55 am. The time for "Sunset" is approximately 8:30 pm. Carrying out the same correction procedure, the latest time of sunset is 8:05 pm. The azimuth of the sun is 0 indicating that it is due south.
It is a little more work to obtain the latest morning and earliest afternoon hours. The latest morning hour is when the sun is due east or when the azimuth indicated on the screen below indicates 90 E. The earliest afternoon hour is when the sun is due west or when the azimuth indicated on the screen below indicates 90 W. The way to determine this is to change the time until each of these values is approached. Don't forget to apply the correction as discussed above to obtain solar time. This is easily done by recording the "DIAL TIME". You need not be overly accurate as the hour lines on the dial will extend beyond these points. It doesn't take a lot of time to do this. Once you have established the morning and afternoon ranges for the hour lines, you can design your sundial. Table 1 and Table 2 shows the calculation performed for a sundial (north/south) located at latitude 50N. Notice that the hour line angles for the am and pm hours are symmetrical about the noon hour line. The issue resources includes a spreadsheet that will perform these calculations for you. This spreadsheet is the same one that is used to design a vertical direct south sundial. When you have determined how large a dial plate you want then you must give some consideration to how large the gnomon should be. The height of the gnomon will determine the path the shadow will take over the dial plate throughout the year.
Note: For more stuff visit: www.mysundial.ca
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Table 1. Hour Line Angle Calculations for direct north sundial.
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Table 2. Hour Line Angle Calculations for direct south sundial.
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Figure 1: Vertical Direct North Sundial. This is a plot of the hour lines for a vertical direct north sundial in 15-minute intervals. A drawing like this can be used as a template to lay out a dial plate. It also shows the dial mounting data
Figure 2: Vertical Direct South Sundial. This is a plot of the hour lines for a vertical direct south sundial in 15-minute intervals. A drawing like this can be used as a template to lay out a dial plate. It also shows the dial mounting details.
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The following three figures illustrate this for three gnomon heights using a dial plate that is fixed in size. As the gnomon height increase the shadow covers more of the plate yet remains on the dial plate. For a very large gnomon the shadow will extend beyond the end of the dial plate for portion of the year. The sundial software package "SHADOWS" generates sundial layouts very quickly and is very good for doing this type of design comparison.
Figure 3: Vertical sundial with gnomon 5 units high .
Figure 4: Vertical sundial with gnomon 15 units high.
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Figure 5: Vertical sundial with gnomon 25 units high.
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Praxis - Troughton & Simms Dividet-Lens Double Image Micrometer by Chris Lord
Introduction A mid C19th example of a double image micrometer manufactured by Troughton & Simms, has been subject to optical analysis, and compared to descriptions of similar contemporaneous micrometers made by the same company. Certain features of this particular micrometer indicate it is unique, and was made for William Lassell in 1858. History The first four lens eyepiece divided-lens double image micrometer was made by Troughton & Simms for the Royal Greenwich Observatory in 1838 [1]. It was designed from first principles by George Airy, based on his analysis of the four-lens achromatic eyepiece [2] and its spherical correction [3]. Airy later published details of a modified four lens micrometer eyepiece in May 1845 [4,5]. Airy's approach was based on what is now termed first order abaxial ray tracing. However rather than get bogged down in trigonometry, which would have entailed tedious calculation in the days of logarithm and trigonometry tables, he derived algebraic expressions for the crossing points and spacings and surface radii of the four lenses. In his 1845 paper [5] he summarised the lens spacing expressions for chromatic and spherical correction in the following terms. Putting p,q,r,s, as the focal lengths of the four lenses, ordered from the telescope objective, and a,b,c, their respective spacings, the algebraic expressions were: 0 = bc - cq -(b+c)r - bs + qr + qs + rs in which the lateral translation of the divided lens introduces no longitudinal chromatic aberration 0 = 3bc - 2(b+c)r-2bs+rs in which the lateral translation of the divided lens produces no lateral chromatic aberration which when combined produce: 0 = 2bc - bs - (b+c)r + q(c - r - s) Airy had William Simms manufacture his new design using the following lens prescription:
p, the focal length of the first lens, is arbitrary. (I estimate it would have been about 2") a, the distance from the first lens to the second, is to be the same as p. q, the focal length of the second or divided lens, = 5. b, the distance from the second lens to the third, = 2. r, the focal length of the third lens, or field-glass, = 1. c, the distance from the third lens to the fourth, = 7/4. s, the focal length of the fourth lens, or eye-glass, = 1.
William Lassel's double image micrometer?
length, and the distance p to s, 9". The micrometer pictured in the introduction is 7"1/4 overall length. Fig. 1 shows a geometric ray first-order ray trace yields the following optical configuration: the object on the left @ x=3.62, y=-0.1 depicts the image formed by the refractor's object glass. The four lenses, p,q,r,s, are spaced in correct proportion. Airy's original and modified construction employed a weak equi-convex positive dividedlens, q. The four lens achromatic eyepiece is an erecting eyepiece. The first lens, p, was interchangeable, and spaced such that, a = p. Shorter focal length first lenses provided higher magnification. Airy states in his 1840 report [6] that with the lowest power first lens the widest measurable separation was ~90"arc. Separating the divided lens produced elliptical Airy discs, and prismatic dispersion, but it was tolerable, and accurate separation measures could be obtained. However the lens division produced a bright diffraction spike perpendicular to the direction of division, and this made position measures awkward. To enable the zero of the position angle to be more readily estimated, a wire was placed in the eye-glass tube at the cross over point. However, although Airy makes no mention of it, the eye lens, s, being a simple positive lens, the image of the wire would have been marred by false colour. Notice also the similarity of the exit beam angle and the beam angle between the first two lenses, p & q. The exit beam is not much steeper, implying the eye lens had a low magnifying power. This in turn meant that a given translation of the divided lens by the micrometer screw, would produce a barely noticeable separation of the star being measured. Airy confirms this to be so, by stating a faster than normal screw was needed. In other words instead of a standard 100tpi (1/100" pitch) screw, a pitch of 40tpi or 50tpi was used. Neither
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The power of the four lens eyepiece is equivalent to that of a single lens 4p/5 focal length. The values are proportions that may be scaled, to which any unit of length may be applied, but in practice Simms used the imperial inch. In practice the original micrometer was about 20" overall
Troughton & Simms Dividet-Lens Double Image Micrometer by Chris Lord
Fig. 1
Fig. 2
Fig. 3
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Airy or Simms specifies the screw pitch, but examining similar micrometers, it appears a screw pitch of 40tpi was adopted. Simms also supplied James Challis with a similar micrometer for the Northumberland refractor [7].
Fig. 2 is a longitudinal section of the 4 lens divided-
lens eyepiece. Conveniently the engraver included an inch scale, from which the lens spacings may be measured, with the following results: a, the distance from the first lens to the second, is to be the same as p = 47/32" b, the distance from the second lens to the third, = 190/32". c, the distance from the third lens to the fourth, = 95/32". This is not the same as Airy's prescription. Airy's design has the ratio b/c = 8/7. Simms prescription for Challis' 4 lens divided-lens eyepiece has the ratio b/c = 190/95 = 2 This gives a value b = 3.5 instead of b = 2, and the sum 2bc - bs - (b+c)r + q(c - r - s) = 2.25. Only when q = 14 does the sum = 0. Perhaps Simms decided to use a very weak second lens, but by so doing image separation would have required a fast screw, and the range would be restricted. The reason Simms may have decided upon a much weaker second lens would be to reduce the loss of light to the duplicated image when the lens segments were separated. Given the accuracy of the engraving, and the fact that a scale was included so the reader could determine the physical dimensions, it does not seem likely that the departure from Airy's prescription can be attributed to artist's licence. Fig.3 is a cross section of the screw box, showing the divided lens, and the micrometer screw. The engraver has gone to the trouble of drawing the screw threads, which have a steep lead angle, indicative of a fast screw. At the meeting of the Royal Astronomical Society on May 10, 1850, the President, Captain William Henry Smyth, related of a further development of the eyepiece micrometer [8], quote: "At the meeting of May 10, the President gave an oral account of a new arrangement of the doubleimage micrometer. Referring to a paper in the Memoirs of the Society, in which the general structure of the four-glass eye-piece, with the second lens (reckoning from the object-glass) divided, is described, and in which the equations of achromaticity are investigated, he showed that three equations only are given between seven quantities (namely, the four focal lengths of the lenses and the three intervals between them), and therefore, that any four of the quantities may be assumed. The circumstance permits an infinity of
different forms of solution. One form, which appeared generally convenient, was indicated in the memoir, and it has been found in practice to be perfectly successful as regards the special object of the theory, and to be subject only to two small practical inconveniences; that the field is rather contracted, and that a rather rapid screw is required for the micrometer, by which one-half of the divided lens is made to slide past the other. The President then stated that he had received a communication from Mr. Valz, of Marseilles, in which that gentleman had pointed out to him that the equations might be satisfied in a form which would give a larger field of view, by using for the divided glass a concave lens; and the President stated that he had immediately perceived that the construction would possess these two further advantages, that a slower screw would suffice, and that, in consequence of the thinness of the lens near the middle, very little light would be lost if the pencils of light were somewhat inclined to the axis of the telescope (the effect of the central thickness of a convex lens being that, if the pencils are at all inclined, a large proportion of the light is lost, more especially for the high magnifying powers.)" Troughton and Simms constructed a micrometer to Valz's new design using the following lens prescription:
p, the focal length of the first lens, is arbitrary. a, the distance from the first lens to the second, is to be the same as p. q, the focal length of the second or divided lens, = -1. b, the distance from the second lens to the third, = 1. r, the focal length of the third lens, or field-glass, = 1. c, the distance from the third lens to the fourth, = 3. s, the focal length of the fourth lens, or eye-glass, = 1.
Fig. 4 shows a geometric ray first-order ray trace
yields the following optical configuration: An example of a Troughton & Simms divided-lens double image micrometer constructed according to Valz's arrangement is held in the collection of the Museum for the History of Science, Oxford. Again, as in Airy's arrangement the position wire would have been marred by false colour. But Valz's idea of using an equi-concave, instead of an equi-convex lens was a good one, inasmuch as not only did it widen the apparent field of view for any particular power of first lens, it also flattened the field somewhat, making the screw constant, almost uniform across the semi-field. This defect was unrecognised by Airy, but pointed out by Professor Frederik Kaiser, of the Leiden Observatory [9]. The problem of elliptical Airy discs resulting from the divided lens segments was addressed in 1858 [10], quote: "The Rev. Mr. Dawes having at the last meeting made a communication containing some sugges29
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tions relative to the obtaining better angles of position than have hitherto procured with the divided eye-glass double-image micrometer, and as I was engaged at the time upon the construction of one for Mr. Lassell, I have been induced to give some attention to the subject. It will be remembered that the Astronomer Royal, when explaining his construction of the instrument, mentioned the difficulty of obtaining good angles of position on account of the elliptic images caused by the transmission of the pencil of rays through segments of circles; but that distances were measurable with extreme accuracy, the form of the star being favourable to this observation. A suggestion having been made at the meeting that Mr. Dawes' plan of fixing, in front of the objectglass, a cap with two circular apertures in contact, might possibly be improved upon; it occurred to me, that the desired improvement would be effected if stops, with circular apertures of suitable diameters, and with their circumference just in contact, the point of contact being over the division of the concave lens, were made to slide into the micrometer itself, as near as practicable to the point where the rays cross to form the image.* Upon trial, this was found to answer, the form of the star being decidedly improved, but of course with the same sacrifice of light as in Mr. Dawes' contrivance. With planets, and other faint objects. I believe there would be no advantage gained in employing the stops, but the manner in which they may be removed, or changed, I consider to be much more convenient than any other method of producing the same effect. In the instrument made for Mr. Lassell, there are four stops to accompany the four first lenses, numbered from 1 to 4, but any one can be used with any other lens, a smaller aperture stop being equivalent to cutting off some of the outer edge of the speculum or object-glass." * Mr. De la Rue, in an instrument constructed for him, had
shutters to slide at the place, to regulate the brightness of one of the images.
I have found an example of a similar instrument as Simms described at the Museum for the History of Science, Oxford (see the images at right). However, this micrometer also has the same reading drum as the previous example, and only 3 stops, plus a filter wedge. The particular micrometer William Simms described, as possessing four first lenses, and four aperture stops, made for William Lassell in 1858, is similar to that made for the Leiden Observatory in 1858, and used for the 1874 Venus Transit [11]. (transits.mhs.ox.ac.uk/browse/onerecord.php?object_id=404).
The micrometer has however a fast screw (40tpi) and a drum divided accordingly.
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It too was also made to Valz's arrangement, but judging from the length of the revolutions scale, possessed a fast 40tpi screw, although the reading drum is similar to the Lassell micrometer. The Leiden micrometer does not possess aperture stops. The focal lengths of the four front lenses, are 1", 3/4", 1/2" & 1/3".
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Properties of the Lassel Micrometer What makes the Lassell micrometer unique, is the four insertable aperture stops plus four first lenses. The micrometer matching William Simms' description exactly and depicted below has been analysed for its optical arrangement, and found to be identical to Simms' modification to the original Valz arrangement, as described by him in 1858 [10]. The eyepiece has been modified by substituting a Symmetrical achromatic eye piece for the last two lenses (r & s), and the lens spacing adjusted as follows:
p, the focal length of the first lens, is arbitrary. a, the distance from the first lens to the second, is to be the same as p. q, the focal length of the second or divided lens, = -1. b, the distance from the second lens to the third, = 35. r, the focal length of the third lens, or field-glass, = 1. c, the distance from the third lens to the fourth, = 1. s, the focal length of the fourth lens, or eye-glass, = 1.
The first lenses are numbered 1 thru' 4, as are the stops.
The spacing between the second and third lens has been increased, and the eye-glass tube modified to accommodate the position wire. In so doing the Symmetrical achromatic eyepiece may be placed with its field lens (the third lens) behind the position wire, and higher powers achieved with a wider field of view. In practice, to provide eye relief, c is reduced from 1 to 08, which introduces an acceptable modicum of lateral chromatic aberration. The advantage of this arrangement is that the position wire (there are a pair of parallel wires narrowly separated in this instance) is not marred by false colour.
Table 1 shows the three prescriptions discussed
Front lenses numbered 1 thru' 4 & one without a number (designated '0').
and Lord's modification to Valz's prescription:
ratios r=s=1, q=-1, b=3.5, c=0.8. The equation 2bc - bs - (b+c)r + q(c-r-s) = -1. Bearing in mind the substitute lenses r & s are achromatic and therefore corrected for longitudinal chromatic and spherical aberration, the only aberration that is under-corrected according to Airy's formula is lateral chromatic aberration. The stops mask this to a large extent. This particular micrometer has a 100 tpi screw and 40 revolutions travel (20 revolutions either side of the zero point). Note the drum head is the same as that on the Leiden micrometer. The four front lenses have focal lengths, #4 - 3/4", #3 - 5/8", #2 13/32", #1 - 9/32". There is also an unnumbered front lens for use when the eyepiece is used to observe either the planets, or to measure exit pupil diameters as a dynameter eyepiece, #0 - 1"3/32 focal length, and a '0' open stop to match. The focal length of the whole eyepiece is equivalent to 9/16 times their focal length. From calibration measures, first lens amplifications were found to be, #0 - A=X1004, #4 - A=X1435, #3 - A=X1621, #2 - A=X2561, #1 - A = X4048. From which A x p(inches) = 1075. With the unmarked first lens separations up to 120"arc maybe measured. Fig. 5-9 show a geometric ray first-order ray trace yields the following optical configuration: Because the first lens is always placed at its focal length from the second lens, the virtual image formed by the first lens always lies in the same place, x=6.12, y=0.94. The relationship between
Table 1.
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The focal length of the divided lens q is -0"81, the achromatic field and eye lenses r & s, 0"832, separation c, 0"63 and the separation of the divided lens and field lens b, 2"875, which gives
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Fig. 4.
Fig. 5. First lens #0 - geometric ray thin lens ray trace - object @ x=1.41, y=-0.2 is image formed by object glass.
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the object position and the first lens focal length may be calculated from the standard thin lens equation 1/p = 1/u + 1/v, where u & v are the object & image distances. The relationship between the first lens amplification of the eyepiece is not so straightforward. It is given by the ratio of the first lens magnification divided by the Barlowed magnification of the second lens, divided by a constant. The constant is governed by the effective focal length of the eyepiece section lenses r & s, & second lens q. Let the efl of r & s = w, then the efl of r,s & q will be qw/q+w-(b+c), where w = rs/r+s-c The first lens magnification is its image distance divided by its object distance. Since the virtual image of the first lens always lies in the same place with respect to the second lens, its image distance is equal to the first lens focal length plus the distance between the second lens and the virtual image of the first lens. Table 2 shows the spreadsheet calculations:
Divided-lens & micrometer screw drum - the drum is divided into 100 divs.
Table 2 (all length units are inches).
The amplification factors A are derived by calibration on known pairs (see section Micrometer in Use below). The first lens magnification is given by m=v/u. The constant k=Z/B is that derived from the calibrated amplifications, k calc is the theoretical value. The deviation from the calibrated values are due to inaccuracies in calibrating the first lens focal lengths, and the eyepiece lenses r & s, and the negative focal length of the second lens q, plus build error. In theory pA=1", hence the first lens amplification is the reciprocal of its focal length in inches (truly an imperial design!). The linear image displacement (LID) produced by a single rotation of the micrometer screw is the screw pitch divided by the amplification factor of the first lens, equating to: first lens '0' LID 0".00996 first lens '4' LID 0".00697 first lens '3' LID 0".00617 first lens '2' LID 0".00390 first lens '1' LID 0".00247
'0' stop in front of divided-lens.
Micrometer screw revolutions scale 0 - 40 revs travel- the zero point is at 20.
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The angular image displacement caused by a single rotation of the micrometer screw is calculated from R=(648000/pi X 0".01/F)/A, which for a 100" focal length object glass is 20".6265arc/A, and since A=1.075/ p, R=(649000/pi X 0".01/F)Xp/1.075.
Divided concave lens.
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The stops are numbered '0', '1', '2', '3', '4'. Stops 1, 2, 3 & 4 are pairs of holes, touching, just as Simms described, varying in size and separation. The '0' stop is a plain hole, intended to be used with the micrometer when measuring planet or exit pupil diameters. The '0' stop hole is 40 drill gauge or 98 thou, the '4' stop 70 drill gauge or 28 thou, '3' stop 74 drill gauge or 225 thou, '2' stop 80 drill gauge or 135 thou, '1' stop micro drill gauge 93 or 75 thou. The '0' stop covers 9.8 revolutions of the micrometer screw. The '4' stop holes are separated by 30thou (3 revs), the '3' stop 20thou (2 revs), the '2' stop 13thou (1.3 revs), the '1' stop 10thou (1 rev). Given the linear displacement is the screw pitch divided by the amplification factor of the first lens, the smallest linear separation of a double star ('1' stop & #1 first lens) would be 0".00247. For a 100" focal length object glass this corresponds to an angular separation of 5".1arc. The widest separation ('4' stop & #4 first lens) 43". 1arc. With the '0' stop in theory the widest separation would be ('0' stop & #0 first lens) 200"arc, but prismatic dispersion limits it to about 120"arc. The implication being, whereas separations could be measured to a greater accuracy than a filar micrometer, doubles close to the resolution limit of the objective were outside its range. Bear in mind the '0' stop is a 98thou circular aperture, that enables pairs across the range to be measured. Using first lens #3 one drum division would equate to 1".25arc. Screw backlash makes it awkward to make such fine measures, although in practice I was able to obtain accuracies less than 0".2arc on bright proximate pairs. The actual spread in values is given in Table 3. LID is in inches, angular displacement in arcsecs.
Eenlargement of the four stops.
loss of light from one component. Taking a specific instance, #2 first lens & '2' stop, intended for 10"arc pairs, it would not be feasible to measure a 14"arc pair because one of the pair would be occulted. One would perforce switch to the #4 first lens & '1' stop. There are 20 possible combinations of double image stops and first lenses covering a range from 62"arc to 5"arc. In practice I found the #1 first lens and the #1 stop unusable, the image was marred by intrusive diffraction, and the prismatic dispersion objectionable. Given this practical limitation consider the separations that could have been measured with the aid of Table 4. Stop '1' & first lens #1 are impractical, so the range of measurable separations are reduced to those in Table 5. The range in separations each stop could accommodate would depend on the size of the Airy disc, which at f/15 would be 0".0004 in yellow light (0.04 revs or 4 drum divs). For a double star with components of equal magnitude, a realistic leeway for each stop would be approximately 4 Airy disc diameters which equates to 0.16 revs, & converted to arc for F=100": '4' 2".3arc; '3' 2".0arc; '2' 1".3arc; '1' 0".82 The separation ranges each combination of first lenses and stops can cover is plotted in bar Chart 1. The separation limits are 4".28arc to 63".93arc. The grey shaded columns are separations measurable using the #1 first lens &/or '1' stop, or unmeasurable with any combination. It is evident there are separations that could not be measured using these stops. A shortcoming Simms in all likelihood did not envisage. I can find no record of double star measures having been made using these double image stops. Simms mentions Warren De la Rue and
Table 3.
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Simms clearly states any stop may be used with any first lens (10), but the idea of using stops to make the elliptical images round, leads to a quantisation effect. The calibrations I carried out were done using the '0' stop only. I don't believe it would be feasible to calibrate each first lens using the double image stops. The shorter focal length first lenses also introduce greater prismatic dispersion for a given lens translation, and the smaller stops cause greater loss of light, so it is better to use a lower power first lens and a wider stop where feasible. There would be a small range either side of the image displacement value the stop could accommodate, but there would be a
35

William Rutter Dawes having used his divided lens micrometer but their micrometers were not fitted with these stops. I found it simpler to tolerate the elliptical Airy discs and use either no stop or the '0' stop. The Micrometer In Use One of the reasons this type of micrometer was not as popular as a filar micrometer is because calibration is a tedious process. This micrometer has in total five first or relay lenses, so there are five screw constants to calibrate. Airy had his principle observer, Robert Main, calibrate the RGO micrometer using timings of wide pairs. The method I adopted entailed taking double distance measures of known pairs over many nights. Calibrated five screw constants and the amplifying power of the relay lenses:
'0' lens A=X1.004 R = 19".56250".4353 '4' lens A=X1.435 R = 13".68860".2073 '3' lens A=X1.621 R = 12".11840".2532 '2' lens A=X2.561 R = 7".67160".2382 '1' lens A=X4.048 R = 4".85230".1304
from which by linear regression R = 19".64/A + 0".002 correlation coefficient = 0.999 999 994 i.e. R = 19".64/A. Once the screw constants have been determined separation measures are just as easy to reduce as with a filar micrometer. The pair of stars and their double images are either strung out equidistant in line, or as a rhomb, and double distance measures taken to eliminate zero point error. e.g.
28APR95 SEEING: II_III #3 lens stop '0' R = 12".11840".2532 alpha GEM rho' = 3".48 (catalogue) 2i = 2043 - 1983 = 60 2i = 2042.5 - 1985 = 57.5 2i = 2043 - 1989 = 54 2i = 2041 - 19089 = 52 2i = 2041 -1987 = 54 rho = 3".3630".131 (probable error) gamma LEO rho' = 4".40 (catalogue) 2i = 2051 - 1981 = 70 2i = 2050 - 1986 = 64 2i = 2053 - 1982 = 71 rho = 4".140".155 (probable error)
Table 5. Table 4.
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separation measures that are within acceptable limits of accuracy, comparable to a filar micrometer. The field of view stopped down is too narrow to readily find and centre a double star, the stop must be withdrawn, the double centred, and brought onto the division using the tilt screw, and then the stop inserted. Conclusion The Troughton & Simms divided-lens double image micrometer was similarly priced to their filar micrometer. In his book, 'The Achromatic Telescope' [12] William Simms includes a trade
Chart 1.
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catalogue, page 12 of which lists item 285, Parallel Wire Position Micrometer at between 8-8s & 1515s, and item 286, Double Image Micrometer, with Position Circle, &c, at 16-16s. Simms makes no mention of his double image micrometer in his book, but does mention the filar micrometer, which was far more popular because it was easier to calibrate. Divided-lens double image micrometers made by Troughton & Simms, surviving in collections of scientific instruments, are extremely rare. Few would have been made, and all to order, and made as one-offs. Similarities in appearance are owing to manufacturing tradition, not mass production. At a time when the artisans who worked for Troughton & Simms in the mid C19th were paid about 10s a week, a scientific instrument costing 16-16s, equivalent to 34 weeks wages, would have been unaffordable. There were very few astronomers who could afford such instruments. Those who could were usually grand amateurs, or professional astronomers procuring instruments for private or university observatories. The small demand for this type of micrometer, and it's relatively rapid development, meant each micrometer made by William Simms, was slightly different from the previous one. Despite extensive searches I have not come across another Troughton & Simms divided-lens double image micrometer identical to the one described by William Simms to the RAS in 1858, and stated as being that which he was at the time making for William Lassell.
References:
The tilt screw is used to bring the image directly onto the division, where the image brightness reaches a maximum.
Given the individual orders that Simms would have fulfilled, and their infrequency, and the exact correspondence between his description and the example in question, it is reasonable to surmise that in all probability it is that made for William Lassell, and presumably in his possession until his death in 1880. Its provenance is unknown. It came into my possession in 1993, and was restored with the assistance H.N. Irving & Son.
[01]. R.G.O. 6/716. 365 Mennim, Eleanor, "Transit Circle, The story of William Simms 1793-1860", ISBN 1850721017. "In mid-December (1839) he (William Simms) had to admit to Airy (G.B.Airy - Astronomer Royal) that he had lost the estimate for a double image eyepiece and position circle." [02]. Airy, George Biddell, B.A.,"On the Principles and Construction of the Achromatic Eye-Pieces of Telescopes..." Cambs. Phil. Trans., XIV, Vol. II, pt. II, pp227-252, & Plate XI, read May 17, 1824, written at Trinity College, April 26, 1824, (1827) [03]. Airy, George Biddell, M.A., "On the Spherical Aberration of Eye-Pieces of Telescopes", Cambs. Phil. Trans., I, Vol. III, Pt. 1, pp 1-63, & Plate I, read May 14 and May 21, 1827, (1830) [04]. Airy, G.B. Esq., Astronomer Royal, "On a new construction of the Divided Eye-glass Double-Image Micrometer". MNRAS, XVI, 16, pp229-231, 1845. [05]. Airy, G.B. Esq., Astronomer Royal, "On a New Construction of the Divided Eye-Glass Double-Image Micrometer". MNRAS, XVI, pp199-209, read May 9, 1845, written April 22, 1845. [06]. Airy, G.B. Esq., Astronomer Royal, "Observations of the Distances and Positions of Double Stars and of the Diameters of Planets, with a double-image eye-piece attached to the South Equatorial, p172-184". Greenwich Observations, 1840, 13, pp lxv-lxxvii. [07]. Challis, James, M.A., F.R.S., F.R.A.S., "Lectures on Practical Astronomy and Astronomical Instruments", 320, pp309-313, & Plate IV, figs. 2 & 3, p335, Cambridge, Deighton, Bell and Co., 1879. [08]. Smyth, William Henry, "Mr. Airy on the divided Eye-piece", MNRAS, X, pp160-161, 1850. [09]. Lohse, J. Gerhard; Copeland, Ralph, "On a New Double Image Micrometer", Annals of the Royal Observatory, Edinburgh, Vol.1, pp152-198, 1902. [10]. Simms, William, Jr. Esq., "Notice of an Improvement of the Double-Image Position Micrometer", MNRAS, XVIII, p64, 1858. [11]. Oudemans, J.A.C., "On the Condition that in a Double-Image Micrometer the value of a Revolution of the Micrometer Screw is independent of the Accommodation of the Eye". MNRAS, XLVIII, pp334-335, May 1888. [12]. Simms, William, F.R.S., F.R.A.S, "The Achromatic Telescope and its various mountings especially The Equatorial". Troughton and Simms, Taylor & Francis, Fleet Street, London, 1852.
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38
Back to Theory Orbital Mechanics by Robert A. Braeunig

Orbital mechanics, also called flight mechanics, is the study of the motions of artificial satellites and space vehicles moving under the influence of forces such as gravity, atmospheric drag, thrust, etc. Orbital mechanics is a modern offshoot of celestial mechanics which is the study of the motions of natural celestial bodies such as the moon and planets. The root of orbital mechanics can be traced back to the 17th century when mathematician Isaac Newton (1642-1727) put forward his laws of motion and formulated his law of universal gravitation. The engineering applications of orbital mechanics include ascent trajectories, reentry and landing, rendezvous computations, and lunar and interplanetary trajectories
Contest Conic Sections Orbital Elements Types of Orbits Newton's Laws of Motion and Universal Gravitation Uniform Circular Motion Motions of Planets and Satellites Launch of a Space Vehicle Position in an Elliptical Orbit Orbit Perturbations Orbit Maneuvers The Hyperbolic Orbit Orbital mechanics, also called flight mechanics, is the study of the motions of artificial satellites and space vehicles moving under the influence of forces such as gravity, atmospheric drag, thrust, etc. Orbital mechanics is a modern offshoot of celestial mechanics which is the study of the motions of natural celestial bodies such as the moon and planets. The root of orbital mechanics can be traced back to the 17th century when mathematician Isaac Newton (1642-1727) put forward his laws of motion and formulated his law of universal gravitation. The engineering applications of orbital mechanics include ascent trajectories, reentry and landing, rendezvous computations, and lunar and interplanetary trajectories. Conic Sections A conic section, or just conic, is a curve formed by passing a plane through a right circular cone. As shown in Figure 1, the angular orientation of the plane relative to the cone determines whether the conic section is a circle, ellipse, parabola, or hyerbola. The circle and the ellipse arise when the intersection of cone and plane is a bounded curve. The circle is a special case of the ellipse in which the plane is perpendicular to the axis of the cone. If the plane is parallel to a generator line of the cone, the conic is called a parabola. Finally, if the intersection is an unbounded curve and the plane is not parallel to a generator line of the cone, the figure is a hyperbola. In the latter case the plane will intersect both halves of the cone, producing two separate curves.
Conic Section Eccentricity, e Semi-major axis Energy Circle Ellipse 0 0<e<1 = radius >0 <0 <0
Parabola Hyperbola
1 >1
infinity <0
0 >0
We can define all conic sections in terms of the eccentricity. The type of conic section is also related to the semi-major axis and the energy. The table below shows the relationships between eccentricity, semi-major axis, and energy and the type of conic section. Satellite orbits can be any of the four conic sections. This page deals mostly with elliptical orbits, though we conclude with an examination of the hyperbolic orbit. Orbital Elements To mathematically describe an orbit one must define six quantities, called orbital elements. They are: Semi-Major Axis, a Eccentricity, e Inclination, i Argument of Periapsis, Time of Periapsis Passage, T Longitude of Ascending Node, An orbiting satellite follows an oval shaped path known as an ellipse with the body being orbited, called the primary, located at one of two points
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39
Orbital Mechanics
called foci. An ellipse is defined to be a curve with the following property: for each point on an ellipse, the sum of its distances from two fixed points, called foci, is constant (see Figure 2). The longest and shortest lines that can be drawn through the center of an ellipse are called the major axis and minor axis, respectively. The semi-major axis is one-half of the major axis and represents a satellite's mean distance from its primary. Eccentricity is the distance between the foci divided by the length of the major axis and is a number between zero and one. An eccentricity of zero indicates a circle. Inclination is the angular distance between a satellite's orbital plane and the equator of its primary (or the ecliptic plane in the case of heliocentric, or sun centered, orbits). An inclination of zero degrees indicates an orbit about the primary's equator in the same direction as the primary's rotation, a direction called prograde (or direct). An inclination of 90 degrees indicates a polar orbit. An inclination of 180 degrees indicates a retrograde equatorial orbit. A retrograde orbit is one in which a satellite moves in a direction opposite to the rotation of its primary. Periapsis is the point in an orbit closest to the primary. The opposite of periapsis, the farthest point in an orbit, is called apoapsis. Periapsis and apoapsis are usually modified to apply to the body being orbited, such as perihelion and aphelion for the Sun, perigee and apogee for Earth, perijove and apojove for Jupiter, perilune and apolune for the Moon, etc. The argument of periapsis is the angular distance between the ascending node and the point of periapsis (see Figure 3). The time of periapsis passage is the time in which a satellite moves through its point of periapsis. Nodes are the points where an orbit crosses a plane, such as a satellite crossing the Earth's equatorial plane. If the satellite crosses the plane going from south to north, the node is the ascending node; if moving from north to south, it is the descending node. The longitude of the ascending node is the node's celestial longitude. Celestial longitude is analogous to longitude on Earth and is measured in degrees counterclockwise from zero with zero longitude being in the direction of the vernal equinox. In general, three observations of an object in orbit are required to calculate the six orbital elements. Two other quantities often used to describe orbits are period and true anomaly. Period, P, is the length of time required for a satellite to complete one orbit. True anomaly, , is the angular distance of a point in an orbit past the point of periapsis, measured in degrees. Types Of Orbits For a spacecraft to achieve Earth orbit, It must be
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launched to an elevation above the Earth's atmosphere and accelerated to orbital velocity. The most energy efficient orbit, that is one that requires the least amount of propellant, is a direct low inclination orbit. To achieve such an orbit, a spacecraft is launched in an eastward direction from a site near the Earth's equator. The advantage being that the rotational speed of the Earth contributes to the spacecraft's final orbital speed. At the United States' launch site in Cape Canaveral (28.5 degrees north latitude) a due east launch results in a "free ride" of 1,471 km/h (914 mph). Launching a spacecraft in a direction other than east, or from a site far from the equator, results in an orbit of higher inclination. High inclination orbits are less able to take advantage of the initial speed provided by the Earth's rotation, thus the launch vehicle must provide a greater part, or all, of the energy required to attain orbital velocity. Although high inclination orbits are less
40
Orbital Mechanics
energy efficient, they do have advantages over equatorial orbits for certain applications. Below we describe several types of orbits and the advantages of each: Geosynchronous orbits (GEO) are circular orbits around the Earth having a period of 24 hours. A geosynchronous orbit with an inclination of zero degrees is called a geostationary orbit. A spacecraft in a geostationary orbit appears to hang motionless above one position on the Earth's equator. For this reason, they are ideal for some types of communication and meteorological satellites. A spacecraft in an inclined geosynchronous orbit will appear to follow a regular figure-8 pattern in the sky once every orbit. To attain geosynchronous orbit, a spacecraft is first launched into an elliptical orbit with an apogee of 35,786 km (22,236 miles) called a geosynchronous transfer orbit (GTO). The orbit is then circularized by firing the spacecraft's engine at apogee. Polar orbits (PO) are orbits with an inclination of 90 degrees. Polar orbits are useful for satellites that carry out mapping and/or surveillance operations because as the planet rotates the spacecraft has access to virtually every point on the planet's surface. Walking orbits: An orbiting satellite is subjected to a great many gravitational influences. First, planets are not perfectly spherical and they have slightly uneven mass distribution. These fluctuations have an effect on a spacecraft's trajectory. Also, the sun, moon, and planets contribute a gravitational influence on an orbiting satellite. With proper planning it is possible to design an orbit which takes advantage of these influences to induce a precession in the satellite's orbital plane. The resulting orbit is called a walking orbit, or precessing orbit. Sun synchronous orbits (SSO) are walking orbits whose orbital plane precesses with the same period as the planet's solar orbit period. In such an orbit, a satellite crosses periapsis at about the same local time every orbit. This is useful if a satellite is carrying instruments which depend on a certain angle of solar illumination on the planet's surface. In order to maintain an exact synchronous timing, it may be necessary to conduct occasional propulsive maneuvers to adjust the orbit. Molniya orbits are highly eccentric Earth orbits with periods of approximately 12 hours (2 revolutions per day). The orbital inclination is chosen so the rate of change of perigee is zero, thus both apogee and perigee can be maintained over fixed latitudes. This condition occurs at inclinations of 63.4 degrees and 116.6 degrees. For these orbits the argument of perigee is typically placed in the southern hemisphere, so the satellite remains above the northern hemisphere near apogee for approximately 11 hours per orbit. This orientation can provide good ground coverage at high northern latitudes. Hohmann transfer orbits are interplanetary trajectories whose advantage is that they consume the least possible amount of propellant. A Hohmann transfer orbit to an outer planet, such as Mars, is achieved by launching a spacecraft and accelerating it in the direction of Earth's revolution around the sun until it breaks free of the Earth's gravity and reaches a velocity which places it in a sun orbit with an aphelion equal to the orbit of the outer planet. Upon reaching its destination, the spacecraft must decelerate so that the planet's gravity can capture it into a planetary orbit. To send a spacecraft to an inner planet, such as Venus, the spacecraft is launched and accelerated in the direction opposite of Earth's revolution around the sun (i.e. decelerated) until it achieves a sun orbit with a perihelion equal to the orbit of the inner planet. It should be noted that the spacecraft continues to move in the same direction as Earth, only more slowly. To reach a planet requires that the spacecraft be inserted into an interplanetary trajectory at the correct time so that the spacecraft arrives at the planet's orbit when the planet will be at the point where the spacecraft will intercept it. This task is comparable to a quarterback "leading" his receiver so that the football and receiver arrive at the same point at the same time. The interval of time in which a spacecraft must be launched in order to complete its mission is called a launch window. Newton's Laws of Motion and Universal Gravitation Newton's laws of motion describe the relationship between the motion of a particle and the forces acting on it. The first law states that if no forces are acting, a body at rest will remain at rest, and a body in motion will remain in motion in a straight line. Thus, if no forces are acting, the velocity (both magnitude and direction) will remain constant. The second law tells us that if a force is applied there will be a change in velocity, i.e. an acceleration, proportional to the magnitude of the force and in the direction in which the force is applied. This law may be summarized by the equation where F is the force, m is the mass of the particle, and a is the acceleration. The third law states that if body 1 exerts a force on body 2, then body 2 will exert a force of equal strength, but opposite in direction, on body 1. This
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Back to Theory
Orbital Mechanics
law is commonly stated, "for every action there is an equal and opposite reaction". In his law of universal gravitation, Newton states that two particles having masses m1 and m2 and separated by a distance r are attracted to each other with equal and opposite forces directed along the line joining the particles. The common magnitude F of the two forces is uniform circular motion is under the influence of a force, called centripetal force, whose magnitude is given by
The direction of F at any instant must be in the direction of a at the same instant, that is radially inward. A satellite in orbit is acted on only by the forces of gravity. The inward acceleration which causes the satellite to move in a circular orbit is the gravitational acceleration caused by the body around which the satellite orbits. Hence, the satellite's centripetal acceleration is g, that is g = 2 v /r. From Newton's law of universal gravitation we 2 know that g = GM /r . Therefore, by setting these equations equal to one another we find that, for a circular orbit,
where G is an universal constant, called the constant of gravitation, and has the value -11 2 2 -8 2 2 6.67259x10 N-m /kg (3.4389x10 lb-ft /slug ). Let's now look at the force that the Earth exerts on an object. If the object has a mass m, and the Earth has mass M, and the object's distance from the center of the Earth is r, then the force that the 2 Earth exerts on the object is GmM /r . If we drop the object, the Earth's gravity will cause it to accelerate toward the center of the Earth. By Newton's second law (F = ma), this acceleration g 2 must equal (GmM /r )/m, or
At the surface of the Earth this acceleration has 2 2 the valve 9.80665 m/s (32.174 ft/s ). Many of the upcoming computations will be somewhat simplified if we express the product GM as a constant, which for Earth has the value 14 3 2 16 3 2 3.986005x10 m /s (1.408x10 ft /s ). The product GM is often represented by the Greek letter . For additional useful constants please see the appendix Basic Constants. For a refresher on SI versus U.S. units see the appendix Weights & Measures. Uniform Circular Motion In the simple case of free fall, a particle accelerates toward the center of the Earth while moving in a straight line. The velocity of the particle changes in magnitude, but not in direction. In the case of uniform circular motion a particle moves in a circle with constant speed. The velocity of the particle changes continuously in direction, but not in magnitude. From Newton's laws we see that since the direction of the velocity is changing, there is an acceleration. This acceleration, called centripetal acceleration is directed inward toward the center of the circle and is given by
Example Problem 1
PROBLEM 1 Calculate the velocity of an artificial satellite orbiting the Earth in a circular orbit at an altitude of 200 km above the Earth's surface. SOLUTION, From Basics Constants,
Given:
Radius of Earth = 6,378.140 km GM of Earth = 3.9860051014 m3/s2
Equation (6),
r = (6,378.14 + 200) 1,000 = 6,578,140 m
v = SQRT[ GM / r ] v = SQRT[ 3.9860051014 / 6,578,140 ] v = 7,784 m/s
Motions of Planets and Satellites Through a lifelong study of the motions of bodies in the solar system, Johannes Kepler (1571-1630) was able to derive three basic laws known as Kepler's laws of planetary motion. Using the data compiled by his mentor Tycho Brahe (1546-1601), Kepler found the following regularities after years of laborious calculations: All planets move in elliptical orbits with the sun at one focus. A line joining any planet to the sun sweeps out equal areas in equal times. The square of the period of any planet about the sun is proportional to the cube of the planet's mean distance from the sun.
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where v is the speed of the particle and r is the radius of the circle. Every accelerating particle must have a force acting on it, defined by Newton's second law (F = ma). Thus, a particle undergoing
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Orbital Mechanics
These laws can be deduced from Newton's laws of motion and law of universal gravitation. Indeed, Newton used Kepler's work as basic information in the formulation of his gravitational theory. As Kepler pointed out, all planets move in elliptical orbits, however, we can learn much about planetary motion by considering the special case of circular orbits. We shall neglect the forces between planets, considering only a planet's interaction with the sun. These considerations apply equally well to the motion of a satellite about a planet. Let's examine the case of two bodies of masses M and m moving in circular orbits under the influence of each other's gravitational attraction. The center of mass of this system of two bodies lies along the line joining them at a point C such that mr = MR. The large body of mass M moves in an orbit of constant radius R and the small body of mass m in an orbit of constant radius r, both having the same angular velocity . For this to happen, the gravitational force acting on each body must provide the necessary centripetal acceleration. Since these gravitational forces are a simple action-reaction pair, the centripetal forces must be 2 equal but opposite in direction. That is, m r must 2 equal M R. The specific requirement, then, is that the gravitational force acting on either body must equal the centripetal force needed to keep it moving in its circular orbit, that is
Example Problem 2
PROBLEM 2 Calculate the period of satellite in PROBLEM 1. SOLUTION, Given: r = 6,578,140 m
2
revolution
for
the
Equation (9), P2 = 4
r3/GM
2 2
P = SQRT[4 P = SQRT[4 P = 5,310 s
r3/GM]
6,578,1403/3.9860051014]
Example Problem 3
PROBLEM 3 Calculate the radius of orbit for a Earth satellite in a geosynchronous orbit, where the Earth's rotational period is 86,164.1 seconds. SOLUTION, Given: P = 86,164.1 s
2
If one body has a much greater mass than the other, as is the case of the sun and a planet or the Earth and a satellite, its distance from the center of mass is much smaller than that of the other body. If we assume that m is negligible compared to M, then R is negligible compared to r. Thus, equation (7) then becomes If we express the angular velocity in terms of the period of revolution, = 2 /P, we obtain
Equation (9), P2 = 4
r3/GM
2
r = [P2GM/(4
r = [86,164.123.9860051014/(4 r = 42,164,170 m
)]1/3
)]1/3
In celestial mechanics where we are dealing with planetary or stellar sized bodies, it is often the case that the mass of the secondary body is significant in relation to the mass of the primary, as with the Moon and Earth. In this case the size of the secondary cannot be ignored. The distance R is no longer negligible compared to r and, therefore, must be carried through the derivation. Equation (9) becomes
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where P is the period of revolution. This is a basic equation of planetary and satellite motion. It also holds for elliptical orbits if we define r to be the semi-major axis (a) of the orbit. A significant consequence of this equation is that it predicts Kepler's third law of planetary motion, that 2 3 is P ~r .
More commonly the equation is written in the equivalent form
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Orbital Mechanics
where a is the semi-major axis. The semi-major axis used in astronomy is always the primary-tosecondary distance, or the geocentric semi-major axis. For example, the Moon's mean geocentric distance from Earth (a) is 384,403 kilometers. On the other hand, the Moon's distance from the barycenter (r) is 379,732 km, with Earth's counterorbit (R) taking up the difference of 4,671 km. Kepler's second law of planetary motion must, of course, hold true for circular orbits. In such orbits both and r are constant so that equal areas are swept out in equal times by the line joining a planet and the sun. For elliptical orbits, however, both and r will vary with time. Let's now consider this case. Figure 5 shows a particle revolving around C along some arbitrary path. The area swept out by the radius vector in a short time interval t is shown shaded. This area, neglecting the small triangular region at the end, is one-half the base times the height or approximately r(r t)/2. This expression becomes more exact as t approaches zero, i.e. the small triangle goes to zero more rapidly than the large one. The rate at which area is being swept out instantaneously is therefore
For any given body moving under the influence of 2 a central force, the value r is constant. Let's now consider two points P1 and P2 in an orbit with radii r1 and r2, and velocities v1 and v2. Since the velocity is always tangent to the path, it can be seen that if is the angle between r and v, then where vsin is the transverse component of v. Multiplying through by r, we have or, for two points P1 and P2 on the orbital path Note that at periapsis and apoapsis, = 90 degrees. Thus, letting P1 and P2 be these two points we get Let's now look at the energy of the above particle at points P1 and P2. Conservation of energy states that the sum of the kinetic energy and the potential energy of a particle remains constant. The kinetic 2 energy T of a particle is given by mv /2 while the potential energy of gravity V is calculated by the equation -GMm/r. Applying conservation of energy we have
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44
Orbital Mechanics
Equation (18),
Ra = Rp/[2GM/(RpVp2)-1] Ra = 6,578,140/[23.9860051014/ (6,578,1407,8502)-1] Ra = 6,805,140 m
Altitude @ apogee = 6,805,140/1,000-6,378.14 = 427.0 km
From equations (14) and (15) we obtain
The eccentricity e of an orbit is given by
Example Problem 6
PROBLEM 6 Calculate the eccentricity of the orbit for the satellite in PROBLEM 5.
Rearranging terms we get
SOLUTION, Given:
Equation (20),
Rp = 6,578,140 m Vp = 7,850 m/s
e = Rp Vp2 / GM - 1 e = 6,578,140 7,8502 / 3.9860051014 - 1 e = 0.01696
Example Problem 4
PROBLEM 4 An artificial Earth satellite is in an elliptical orbit which brings it to an altitude of 250 km at perigee and out to an altitude of 500 km at apogee. Calculate the velocity of the satellite at both perigee and apogee. SOLUTION, Given: Rp = = Ra = = (6,378.14 6,628,140 (6,378.14 6,878,140 + 250) 1,000 m + 500) 1,000 m
If the semi-major axis a and the eccentricity e of an orbit are known, then the periapsis and apoapsis distances can be calculated by
Example Problem 7
PROBLEM 7 A satellite in Earth orbit has a semi-major axis of 6,700 km and an eccentricity of 0.01. Calculate the satellite's altitude at both perigee and apogee. SOLUTION, Given: a = 6,700 km e = 0.01
Equations (16) and (17),
Vp = SQRT[2GMRa/(Rp(Ra+Rp))] Vp = SQRT[23.98600510146,878,140/ (6,628,140(6,878,140+6,628,140))] Vp = 7,826 m/s
Va = SQRT[2GMRp/(Ra(Ra+Rp))] Va = SQRT[23.98600510146,628,140/ (6,878,140(6,878,140+6,628,140))] Va = 7,542 m/s
Equation (21) and (22),
Rp = a (1 - e) Rp = 6,700 (1 - .01) Rp = 6,633 km
Example Problem 5
PROBLEM 5 A satellite in Earth orbit passes through its perigee point at an altitude of 200 km above the Earth's surface and at a velocity of 7,850 m/s. Calculate the apogee altitude of the satellite. SOLUTION, Given: Rp = (6,378.14 + 200) 1,000 = 6,578,140 m Vp = 7,850 m/s
Altitude @ perigee = 6,633 - 6,378.14 = 254.9 km Ra = a (1 + e) Ra = 6,700 (1 + .01) Ra = 6,767 km
Altitude @ apogee = 6,767 - 6,378.14 = 388.9 km
Back to Theory
Launch of a Space Vehicle The launch of a satellite or space vehicle consists of a period of powered flight during which the vehicle is lifted above the Earth's atmosphere and accelerated to orbital velocity by a rocket, or launch vehicle. Powered flight concludes at burn-
45
Orbital Mechanics
out of the rocket's last stage at which time the vehicle begins its free flight. During free flight the space vehicle is assumed to be subjected only to the gravitational pull of the Earth. If the vehicle moves far from the Earth, its trajectory may be affected by the gravitational influence of the sun, moon, or another planet. A space vehicle's orbit may be determined from the position and the velocity of the vehicle at the beginning of its free flight. A vehicle's position and velocity can be described by the variables r, v, and , where r is the vehicle's distance from the center of the Earth, v is its velocity, and is the angle between the position and the velocity vectors, called the zenith angle (see Figure 7). If we let r1, v1, and 1 be the initial (launch) values of r, v, and , then we may consider these as given quantities. If we let point P2 represent the perigee, then equation (13) becomes
grees. Calculate the satellite's altitude at perigee and apogee. SOLUTION, Given: r1 = (6,378.14 + 250) 1,000 = 6,628,140 m v1 = 7,900 m/s = 89o
Equation (26),
(Rp/r1)1,2 = (-CSQRT[C2-4(1-C)-sin2 (2 (1 - C)) where
])/
(Rp / r1)1,2 = (-1.927179SQRT[1.9271792-4 -0.927179-sin2(89)])/ (2 -0.927179) (Rp / r1)1,2 = 0.996019 and 1.082521 Rp = 6,628,140 0.996019 Rp = 6,601,750 m
C = 2GM/(r1 v12) C = 23.9860051014/(6,628,1407,9002) C = 1.927179
Perigee Radius, Rp = Rp1 = r1 (Rp / r1)1
Altitude @ perigee = 6,601,750/1,000-6,378.14 = 223.6 km Apogee Radius, Ra = Rp2 = r1 (Rp / r1)2 Ra = 6,628,140 1.082521 Ra = 7,175,100 m
Substituting equation (23) into (15), we can obtain an equation for the perigee radius Rp.
Altitude @ apogee = 7,175,100/1,000-6,378.14 = 797.0 km
Multiplying through by we get
2 2 2 -Rp /(r1 v1 )
and rearranging,
Equation (26) gives the values of Rp and Ra from which the eccentricity of the orbit can be calculated, however, it may be simpler to calculate the eccentricity e directly from the equation
Example Problem 9 Note that this is a simple quadratic equation in the 2 ratio (Rp/r1) and that 2GM /(r1 v1 ) is a nondimensional parameter of the orbit. Solving for (Rp/r1) gives
PROBLEM 9 Calculate the eccentricity of the orbit for the satellite in PROBLEM 8. SOLUTION, Given: r1 = 6,628,140 m v1 = 7,900 m/s = 89o
Equation (27),
Like any quadratic, the above equation yields two answers. The smaller of the two answers corresponds to Rp, the periapsis radius. The other root corresponds to the apoapsis radius, Ra. Please note that in practice spacecraft launches are usually terminated at either perigee or apogee, i.e. = 90. This condition results in the minimum use of propellant. Example Problem 8
PROBLEM 8 A satellite is launched into Earth orbit where its launch vehicle burns out at an altitude of 250 km. At burnout the satellite's velocity is 7,900 m/s with the zenith angle equal to 89 de-
e = SQRT[(r1v12/GM-1)2sin2 +cos2 ] e = SQRT[(6,628,1407,9002/ 3.9860051014-1)2sin2(89)+cos2(89)] e = 0.0416170
Back to Theory
To pin down a satellite's orbit in space, we need to know the angle , the true anomaly, from the periapsis point to the launch point. This angle is given by
46
Orbital Mechanics
Example Problem 10
PROBLEM 10 Calculate the angle from perigee point to launch point for the satellite in PROBLEM 8. SOLUTION, Given: r1 = 6,628,140 m v1 = 7,900 m/s = 89o Equation (32), a = 1 / ( 2 / r1 - v12 / GM ) a = 1/(2/6,628,140-7,9002/3.9860051014)) a = 6,888,430 m
Equation (28), tan tan tan
= (r1v12/GM)sin
= (6,628,1407,9002/ 3.9860051014)sin(89)cos(89)/ [(6,628,1407,9002/3.9860051014)sin2(89)-1] = 0.48329
[(r1v12/GM)sin2
cos
-1]
= arctan(0.48329) = 25.794o
In most calculations, the complement of the zenith angle is used, denoted by . This angle is called the flight-path angle, and is positive when the velocity vector is directed away from the primary as shown in Figure 8. When flight-path angle is used, equations (26) through (28) are rewritten as follows:
If e is solved for directly using equation (27) or (30), and a is solved for using equation (32), Rp and Ra can be solved for simply using equations (21) and (22). Orbit Tilt, Rotation and Orientation Above we determined the size and shape of the orbit, but to determine the orientation of the orbit in space, we must know the latitude and longitude and the heading of the space vehicle at burnout. Figure 9 on next page illustrates the location of a space vehicle at engine burnout, or orbit insertion. is the azimuth heading measured in degrees clockwise from north, is the geocentric latitude (or declination) of the burnout point, is the angular distance between the ascending node and the burnout point measured in the equatorial plane, and is the angular distance between the ascending node and the burnout point measured in the orbital plane. 1 and 2 are the geographical longitudes of the ascending node and the burnout point at the instant of engine burnout. Figure 10 pictures the orbital elements, where i is the inclination, is the longitude at the ascending node, is the argument of periapsis, and is the true anomaly. If , , and 2 are given, the other values can be calculated from the following relationships:
The semi-major axis is, of course, equal to (Rp+Ra)/2, though it may be easier to calculate it directly as follows:
Back to Theory
Example Problem 11
PROBLEM 11 Calculate the semi-major axis of the orbit for the satellite in PROBLEM 8. SOLUTION, Given: r1 = 6,628,140 m v1 = 7,900 m/s
In equation (36), the value of is found using equation (28) or (31). If is positive, periapsis is west of the burnout point (as shown in Figure 10); if is negative, periapsis is east of the burnout point. The longitude of the ascending node, , is measured in celestial longitude, while 1 is geographical longitude. The celestial longitude of the ascending node is equal to the local apparent sidereal time, in degrees, at longitude 1 at the time of engine burnout. Sidereal time is defined as the hour angle of the vernal equinox at a specific locality and time; it has the same value as the right ascension of any celestial body that is crossing the
47
Orbital Mechanics
local meridian at that same instant. At the moment when the vernal equinox crosses the local meridian, the local apparent sidereal time is 00:00 (could be used any sidereal time calculation). Example Problem 12
PROBLEM 12 For the satellite in PROBLEM 8, burnout occurs 2000-10-20, 15:00 UT. The geocentric coordinates at burnout are 32o N latitude, 60o W longitude, and the azimuth heading is 86o. Calculate the orbit's inclination, argument of perigee, and longitude of ascending node. SOLUTION, Given:
2
= 86o
= 32o
From PROBLEM 10, Equation (33), = 25.794o
= -60o
Equations (34) and (36), tan( ) = tan( = 83.630o = -
cos(i) = cos( ) sin( ) cos(i) = cos(32) sin(86) i = 32.223o ) / cos( )
determined from the semi-major axis of the orbit as follows:
tan( ) = tan(32) / cos(86)
= 83.630 - 25.794 Equations (35) and (37), tan( tan(

1 1 1
= 57.836o
) = sin( = 82.483o
2
) = sin(32) tan(86) -
) tan( )
This solution will give the average position and velocity, but satellite orbits are elliptical with a radius constantly varying in orbit. Because the satellite's velocity depends on this varying radius, it changes as well. To resolve this problem we can define an intermediate variable E, called the eccentric anomaly, for elliptical orbits, which is given by
= -60 - 82.483 = -142.483o = Sidereal time at -142.483 longitude, 2000-10-20, 15:00 UT = 7h 27' 34" = 111.892o
where is the true anomaly. Mean anomaly is a function of eccentric anomaly by the formula For small eccentricities a good approximation of true anomaly can be obtained by the following 3 formula (the error is of the order e ): The preceding five equations can be used to (1) find the time it takes to go from one position in an orbit to another, or (2) find the position in an orbit after a specific period of time. When solving these equations it is important to work in radians rather than degrees, where 2 radians equals 360 degrees. Example Problem 13
PROBLEM 13 A satellite is in an orbit with a semi-major axis of 7,500 km and an eccentricity of 0.1. Calculate the time it takes to move from a
Back to Theory
Position in an Elliptical Orbit Johannes Kepler was able to solve the problem of relating position in an orbit to the elapsed time, t-to, or conversely, how long it takes to go from one point in an orbit to another. To solve this, Kepler introduced the quantity M, called the mean anomaly, which is the fraction of an orbit period that has elapsed since perigee. The mean anomaly equals the true anomaly for a circular orbit. By definition, where Mo is the mean anomaly at time to and n is the mean motion, or the average angular velocity,
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Orbital Mechanics
position 30 degrees past perigee to 90 degrees past perigee. SOLUTION, Given: a = 7,500 1,000 = 7,500,000 m e = 0.1 tO = 0 METHOD #2, High Accuracy: Equation (41),
M = E - e sin E 2.53755 = E - 0.1 sin E
= 30 deg
= 90 deg
/180 = 0.52360 radians
Equation (40),
By iteration, E = 2.58996 radians cos E = (e + cos cos ) / (1 + e cos )
/180 = 1.57080 radians
Equation (40), cos E = (e + cos Eo = arccos[(0.1+cos(0.52360))/ (1+0.1 cos(0.52360))] Eo = 0.47557 radians ) / (1 + e cos )
Rearranging variables gives,
= (cos E - e) / (1 - e cos E)
= arccos[(cos(2.58996) - 0.1) / (1 - 0.1 cos(2.58996)] = 2.64034 = 151.3 degrees
E = arccos[(0.1+cos(1.57080))/ (1+0.1cos(1.57080))] E = 1.47063 radians Equation (41), M = E - e sin E
Equation (39),
M = 1.47063 - 0.1 sin(1.47063) M = 1.37113 radians
Mo = 0.47557 - 0.1 sin(0.47557) Mo = 0.42978 radians
At any time in its orbit, the magnitude of a spacecraft's position vector, i.e. its distance from the primary body, and its flight-path angle can be calculated from the following equations:
Equation (38),
n = SQRT[ GM / a3 ] n = SQRT[ 3.9860051014 / 7,500,0003 ] n = 0.00097202 rad/s M - Mo = n (t - tO)
And the spacecraft's velocity is given by,
t = tO + (M - Mo) / n t = 0 + (1.37113 - 0.42978) / 0.00097202 t = 968.4 s
Example Problem 15
PROBLEM 15 For the satellite in problems 4.13 and 4.14, calculate the length of its position vector, its flight-path angle, and its velocity when the satellite's true anomaly is 225 degrees. SOLUTION, Given: a = 7,500,000 m e = 0.1
Example Problem 14
PROBLEM 14 The satellite in PROBLEM 13 has a true anomaly of 90 degrees. What will be the satellite's position, i.e. it's true anomaly, 20 minutes later? SOLUTION, Given: a = 7,500,000 m e = 0.1 tO = 0 t = 20 60 = 1,200 s
O
Equations (43) and (44),
= 225 degrees
From PROBLEM 13,
= 90
/180 = 1.57080 rad
r = a(1-e2)/(1+ecos ) r = 7,500,000(1-0.12)/(1+0.1cos(225)) r = 7,989,977 m = arctan[esin = arctan[0.1sin(225)/(1+0.1cos(225))] Equation (45), = -4.351 degrees /(1+ecos )]
Equation (38),
Mo = 1.37113 rad n = 0.00097202 rad/s M - Mo = n (t - tO)
Back to Theory
METHOD #1, Low Accuracy: Equation (42),
M = Mo + n (t - tO) M = 1.37113 + 0.00097202 (1,200 - 0) M = 2.53755
v = SQRT[GM(2/r-1/a)] v = SQRT[3.9860051014(2/7,989,977-1/ 7,500,000)] v = 6,828 m/s
~ M + 2 e sin M + 1.25 e2 sin 2M ~ 2.53755 + 2 0.1 sin(2.53755) + 1.25 0.12 sin(2 2.53755) ~ 2.63946 = 151.2 degrees
To be continued
49
Astronomical Computing - Globular Cluster and Cyber Sky by SPACEACADEMY.NET
The two simple programs written in BASIC simulates globular clusters and sky pictorially. The user specifies the number of stars that the cluster is to contain. The resulting simulation is then plotted out.
Globular Cluster A globular cluster is a very compact spherical group of stars. It may typically contain 100,000 to ten million stars, and is usually found in the halo of the galaxy rather than in the disc. The stars in a globular cluster are population II stars which are red and thought to be older stars deficient in elements heavier than helium. Globular clusters are typically several hundred light years in diameter. The image above is a computer simulation of a globular cluster. A random number generator is used to determine both the angular and radial position of each star in the cluster. The angle is specified by a uniform distribution, but the radial position is given by a Gaussian distribution. Approximately one hundred globular clusters have been found in the halo of the Milky Way. The most famous in the southern sky are Omega Centauri and 47 Tucanae. These are shown below for comparison with the simulated cluster. The simulation was done with a very simple QBASIC program whose source code is given below so that you may create your own globular clusters. Cyber Sky Computer programs can be used to produce star images. A random number generator is used to determine both the position of a star in the "sky" and also its brightness. The apparent brightness of the star is varied by a combination of both the actual brightness of the point and its size. The sky images shown above and below were made with a very simple QBASIC program whose source code is given below so that you may create your own 'cyber sky images'. Study the program and note how the number of stars varies according to their brightness. More computer generated star images are shown below. You might enjoy devising constellations for the star groupings.
Astronomical Computing
Top: Omega Centauri. Bottom: 47 Tucanae.
Credit: ESO
Note: For more stuff about space and rockets please visit: www.spaceacademy.net
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Listing 1 of 1
'Generate Globular Cluster [GCLUSTER.BAS] DIM level(3) 'magnitude levels SCREEN 12 '640x480 pixels PI = 3.14159 'to put angle in radians FOR star = 1 TO 100000 '100,000 stars in cluster CLR = 8 'faintest star brightness IF star MOD 5 = 0 THEN CLR = 7 'intermediate start brightness IF star MOD 25 = 0 THEN CLR = 15 'brightest stars brightness theta = 2 * PI * RND 'select a radom angle 0 to 2pi 'now compute a radius with gaussian distribution about cluster centre radius = (RND + RND + RND + RND + RND + RND - 3!) * 100 xp = 320 + radius * COS(theta) 'compute x coordinate of star yp = 240 + radius * SIN(theta) 'compute y coordinate of star PSET (xp, yp), CLR 'and plot NEXT star DO WHILE INKEY$ <> CHR$(27) 'wait until ESC key is pressed LOOP END 'then terminate 'Generate starry sky [STARS.BAS] DIM level(3) 'magnitude levels RANDOMIZE TIMER 'so that each sky is different SCREEN 12 '640x480 pixels m1 = 3 'average number of mag 1 stars (default 3) r = 8 'star number ratio per magnitude (default 8) totalstars = m1 * (1 + r + r * r + r * r * r) '# of stars in the sky level(1) = m1 / totalstars 'compute levels to make level(2) = m1 * (1 + r) / totalstars '4 different magnitudes level(3) = m1 * (1 + r + r * r) / totalstars DO 'this is the loop that generates a new sky CLS 'clear screen/sky FOR i = 1 TO totalstars 'generate stars one by one xp = RND * 640 'x position on the screen yp = RND * 480 'y position on the screen magtst = RND 'generate a number to determine magnitude mag = 4 'start by assuming faintest star IF magtst < level(3) THEN mag = 3 'then brighten if IF magtst < level(2) THEN mag = 2 'generated random number is IF magtst < level(1) THEN mag = 1 'within specified level SELECT CASE mag 'now plot star according to magnitude CASE 4 PSET (xp, yp), 8 'faintest star (try changing colour to 7?) CASE 3 PSET (xp, yp), 15 'brightest star with a single point CASE 2 CIRCLE (xp, yp), 1, 15 'increase app brightness by increasing size PAINT (xp, yp), 15 CASE 1 CIRCLE (xp, yp), 1.5, 15 'brightest stars have largest area PAINT (xp, yp), 15 END SELECT NEXT i 'go back and plot all stars until finished DO a$ = INKEY$ 'wait for a keyboard input LOOP WHILE a$ <> CHR$(27) AND a$ <> "q" 'ESC generates new sky LOOP WHILE a$ <> "q" 'q quits program END 'program end
51
Modelled Globular Cluster.
Credit: SPACEACADEMY.NET
52
Cyber Sky.
Credit: SPACEACADEMY.NET
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58
Software Review MODAS NG Update - Mirror Testing

After many years of development MODAS NG ATM edition is near competition. This will be the last but one update. Only a few features are not rewritten in the new vector graphic. As I quit in the editor notes, MODAS NG will available in the next few years only as freeware (no commercial version will be available by some private reason). Still this MODAS NG ATM freeware will allow the users to enjoy many powerful features. Until Christmas will be available the final freeware release and I keep you informed.
m much pleasured to apply the new update of I MODAS NG ATM release. Of course the numbers of rewritten features maybe look not too reach, but the work was enormously. What is new in this update?
I was able to adapt four analyses to the new vector graphic - Foucaultgrams, Ronchigrams, MiullesLacroix Data Reduction and the real mirror profile by Roger Sinnott and Dmitri Macsutov. Two analyses - Ronchi-Mosby Null Test and Teribizh Test currently could not be adopted, maybe in the feature. Under development is too the Texerau Mirror Profile. I have optimized the settings of all mirrors tests some properties was removed or added and bugs have bin fixed. For example all dialogs allow the user to enter his own Title of the test and the assign of the design title (if a dsg file was opened) work now properly. Similar to other analyses like RMS Spot Size vs. Field Angle I have added the property Scale Grid Type (see below) the both Mirrors Profile. All these analyses will be in the feature improved and made easier to use. Unlimited number of series (mirror test trials) will be added, with additional reporting features. What is still open? Adaptation to the vector graphic of the Geometrical analyses - Encircled Energy and MTF analyses and the Tabular and graphical Seidel aberrations. I hope all this comes with the next final update. After the final update, I wish to start with the optimization, tolerancing, physical optics modules and the 3D optical layout. Really I have all theoretical stuff needed for the development and improvement of these features! The 3D optical layout will be based on the Open GL. Important bug fixes related all analyses was applied. After a window was maximized, the graphic was not redraw correct! I hope you enjoy this release!
Top: The Mirror Tree Selection. Middle: The Foucault Test settings dialog. Bottom: The Ronchi Test settings dialog.
Computer and Telescopes
59
MODAS NG Update - Mirror Testing
Computer and Telescopes Optical Computing
The Knife-Edge data reduction setting dialog. It allow the user to create up to 5 different series (in the feature unlimited number of series). The settings dialog is used by both mirrors profile analyse by Roger Sinnott and Dmitri Maksutov.
60
Millies-Lacroix Graph Approach in different graphic representation and styles.
61
Left: Mirror Real Profil by Roger Sinnott in different graphic stiles. Right: Mirror Real profile by Dmitri Maksutov in different graphic styles.
62
Through Focus Foucaultgrams in different colors.
63
Left: Foucaultgrams in ROC. Right: Ronchigrams outside ROC.
64
Through Focus Ronchigrams in different colors.
65
Ronchigrams in ROC.
66
Left: Ronchigrams inside ROC. Right: Ronchigrams outside ROC.
67
News
Neil Armstrong (1930-2012)
Neil Armstrong, First Man on the Moon, Dies at 82.
News
68
News
His death was reported at 2:45 p.m. ET. Armstrong commanded the Apollo 11 spacecraft that landed on the moon on July 20, 1969, and he radioed back to Earth the historic news: Thats one small step for a man, one giant leap for mankind. In a statement issued by the White House, U.S. President Barack Obama said Today, Neils spirit of discovery lives on in all the men and women who have devoted their lives to exploring the unknown including those who are ensuring that we reach higher and go further in space. That legacy will endure - sparked by a man who taught us the enormous power of one small step. Neil Armstrong, along with fellow astronauts Buzz Aldrin, Michael Collins and John Glenn, were honored with the Congressional Gold Medal on November 16, 2011.
The first man on the moon is no more. Legendary astronaut Neil Armstrong, the first man to set foot on the moon, has died at age 82.
On August 25, 2012 we mourn the loss of a true hero and icon of a generation, if not an entire century: Neil Alden Armstrong, former NASA astronaut and first person to set foot on the Moon, has passed away due to complications from cardiovascular surgery. Armstrong had recently turned 82 years old on August 5. His family has issued the following statement: We are heartbroken to share the news that Neil Armstrong has passed away following complications resulting from cardiovascular procedures. Neil was our loving husband, father, grandfather, brother and friend. Neil Armstrong was also a reluctant American hero who always believed he was just doing his job. He served his Nation proudly, as a navy fighter pilot, test pilot, and astronaut. He also found success back home in his native Ohio in business and academia, and became a community leader in Cincinnati. He remained an advocate of aviation and exploration throughout his life and never lost his boyhood wonder of these pursuits. As much as Neil cherished his privacy, he always appreciated the expressions of good will from people around the world and from all walks of life. While we mourn the loss of a very good man, we also celebrate his remarkable life and hope that it serves as an example to young people around the world to work hard to make their dreams come true, to be willing to explore and push the limits, and to selflessly serve a cause greater than themselves.
Neil Armstrong (1930-2012)
(Source: Universe Today/Jason Major)
Harry Harrison (1925-2012) Harry Harrison, the American science fiction writer best known for the Stainless Steel Rat comic space opera series and the dystopian Make Room! Make Room! has died at the age of 87. He also parodied the genre in his Bill the Galactic Hero books, seeing his work as anti-war and antimilitaristic. Brian Aldiss, who worked with Harrison on criticism and editing science fiction anthologies, called him "a constant peer and great family friend". Harrison's first novel, Deathworld, was published in 1960, with the Stainless Steel Rat appearing for the first time a year later. "Slippery Jim" diGriz, the books' anti-hero, whose latest appearance was in 2010, was, one admirer pointed out on Wednesday, a "rogue smuggler" created years before Han Solo in the Star Wars films. The central idea of Make Room! Make Room!, his 1966 novel in which a critical food shortage in overpopulated New York means a food substitute is needed, was used in the 1973 film Soylent Green, starring Charlton Heston.
News ATM Update
For those who may ask what they can do to honor Neil, we have a simple request. Honor his example of service, accomplishment and modesty, and the next time you walk outside on a clear night and see the moon smiling down at you, think of Neil Armstrong and give him a wink.
American science fiction author Harry Harrison, who also created the Stainless Steel Rat comic space opera series, has died aged 87.
69
News
News ATM Update
Harry Harrison passed away in the early hours of Wednesday 15th August, 2012. Credit: Harry Harrison News Blog
70
News
Harrison, an advocate of the international language Esperanto, which appears in several of his books, was born in Stamford, Connecticut, in 1925and also lived for periods in Mexico, England, Ireland, Denmark and Italy. After service in the Second World War and art study, he ran a studio selling illustrations to comics and science fiction magazines; He married Joan (ne Merkler) in 1954 in New York. She died from cancer in 2002. They had two children, Todd and Moira.
(Source: Guardian)
Multiple Dinosaur Tracks Confirmed at NASA Center At NASAs Goddard Space Flight Center in Greenbelt, MD, where some of the worlds most advanced research in space technology is being performed on a daily basis, paleontologists have discovered ancient evidence of dinosaurs on the Centers wooded campus - at least two, possibly a mother and child, crossed that way between 112 and 110 million years ago and left their muddy footprints as proof. The tracks of two nodosaurs - short, stocky and heavily-armored herbivorous dinosaurs - have been confirmed by dinosaur tracker Ray Stanford and USGS emeritus paleontologist Dr. Robert Weems. The second track is a smaller version of the first. The first, larger footprint was announced by Stanford on August 17, 2012. When Dr. Weems was called in to verify, the smaller print was discovered within the first, evidence that they were made around the same time and leading researchers to suggest it may have been a motherand-child pair. It looks to be a manus (front foot) print of a much smaller dinosaur than the first one, but it looks to be the same type, Weems said of the second track. If the one that came through was a female, it may have had one or more young ones following along. If youve seen a dog or cat walking with its young, they kind of sniff around and may not go in the same direction, but they end up in the same place. Its thought that the nodosaurs were moving quickly since the tracks dont show strong imprints of the animals heels. Still, the ruddy Cretaceousera mud preserved their brief passage well - even as millions of years went by. This was a large, armored dinosaur, Stanford said. Think of it as a four-footed tank. It was quite heavy, theres a quite a ridge or push-up here. Subsequently the sand was bound together by iron-oxide or hematite, so it gave us a nice preservation, almost like concrete. The next steps will be to have the site analyzed to
This imprint shows the right rear foot of a nodosaur - a low-slung, spiny leaf-eater - apparently moving in haste as the heel did not fully settle in the cretaceous mud, according to dinosaur tracker Ray Stanford. It was found recently on NASA's Goddard Space Flight Center campus and is being preserved for study. Credit: Ray Stanford
determine whether further excavation is called for, and possibly to extract and preserve the existing footprints. Space scientists may walk along here, and theyre walking exactly where this big, bungling heavy armored dinosaur walked, maybe 110 to 112 million years ago. - Ray Stanford
With Proposed Cuts, Can the US Continue to be a Leader in Astronomy? Q & A with NOAO Director David Silva Report from this August, 2012 issued by the National Science Foundations Division of Astronomical Sciences suggested de-funding several ground-based observatories along with other money-saving strategies to help offset budget shortfalls in US astronomy which have been projected to be as much as 50%. The report recommended the closure of iconic facilities such as the Very Long Baseline Array (VLBA) and the Green Bank Radio Telescope, as well as shutting down four different telescopes at the Kitt Peak Observatory by 2017. Universe Today (UT) talked with the Director of the National Optical Astronomy Observatory (NOAO), Dr. David Silva for his reactions to the report. Universe Today: What is your initial reaction to the STP portfolio review: David Silva: Its disappointing, but not completely unexpected. I think the biggest challenge for the overall US community is theyre going to lose access to a lot of world-class, cutting-edge facilities. This is roughly somewhere between eight hundred to a thousand nights of open access time which is going to be defunded over the next three years or so. Thats a huge culture change for US astronomy. UT: Do you see this affecting the researchers at smaller facilities and universities the most?
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Top: Fossilized nodosaur footprints discovered at NASAs Goddard Space Flight Center in Maryland. Bottom: Dinosaur tracker Ray Stanford describes the cretaceous-era nodosaur track he found on the Goddard Space Flight Center campus with Dr. Robert Weems, emeritus paleontologist for the USGS who verified his discovery. Credit: NASA/GSFC/Rebecca Roth
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federal level and there is going to be a squeeze now. I think that one of the choices were going face as there is this squeeze and people begin to leave the field, how do we make sure that the those who are still in the field - especially our younger colleagues - that they are given the mentoring and nurturing and support they need to have vital careers. But theres a growing mismatch between the numbers of people who want funding and the funding that is available, theres no two ways about it.
The Kitt Peak Observatory. Credit: Universe Today
Silva: Definitely. Clearly, the situation is now that if youre at an institution that has its own facility, everything should be OK. But if youre at an institution that does not have access to its own facility, youre in a bad situation. So that naturally segregates the bigger universities versus the smaller universities. I should say there is a caveat, in that we are in an era now in professional astronomy where surveys are now becoming a much stronger component of what we do. Surveys are the big wide-field surveys both from space and from the ground which are producing massive datasets that are open to everyone. So, whats really happening is this culture change from people having to compete for one or two nights a year on a telescope to potentially working on the big datasets. So, how that transition occurs remains to be seen. But the loss of all these open access nights will definitely be a shock to the system. UT: Do you see the new report as being overly pessimistic or do you think its spot on of whats actually going to be taking place in astronomy next few years, such as in one scenario which described that only 50% of projected funding will be available? Silva: I have no opinion on that. That was a boundary condition that the report used, and if I could predict that I would be in a different industry! UT: Do you see any potential silver lining here, that this kind of tight funding could streamline things, or could help in the persistent mismatch between the production rate of Ph.D.s and the number of tenure-track faculty or long-term astronomy positions that the report talked about? Silva: No. I think the higher-level issue is that astronomy in the last 20 years has been a field where the number of people who are professional astronomers has grown in this country because of a fortuitous funding cycle from all three of the major funding agents, NASA, NSF and the Department of Energy. But we are now in a downward cycle in funding for astronomy at the
UT: Any final thoughts or things that you think are people Im important for people to know about? Silva: One of the opportunities that it creates on Kitt Peak is the ability to continue to move forward on our BigBOSS collaboration, which is a proposal to put a 5,000 target, multi-object spectrograph on the 4-meter Mayall telescope at Kitt Peak National Observatory, which allows you to do a large dark energy characterization experiment. The instrument is also exceptionally powerful for doing a variety of other investigations like galactic archaeology to map out kinematics in the galaxy, the chemical composition and the motions of galaxies and stars, and other very large data projects like that. This report was actually quite supportive of that project moving forward. So even though reports recommend the NSF divest funding in the Mayall Telescope as an open-access telescope, it suggests there are ways forward to convert it from an open access platform to a survey facility. And thats, I think, a silver lining in this. It doesnt solve that cultural issue, but it was does mean we can continue to do high impact science with that instrument. But I do see this as a big cultural change. A key question perhaps is, does the US have strong national observatory or not? And this report is leaning in the direction of not.
(Source: Universe Today/Nancy Atkinson)
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Found: Two Exact Matches to the Milky Way Galaxy Heres something astronomers havent seen before: galaxies that look just like our own Milky Way. Its not that our spiral-armed galaxy is rare but instead the whole neighborhood in which we reside seems to be unusual. Until now, a galaxy paired with close companions like the Magellanic Clouds has not been found elsewhere. But using data from a new radio astronomy survey, astronomers found two Milky Way look-alikes and several others that were similar. Weve never found another galaxy system like the Milky Way before, which is not surprising consider-
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havent been able to tell just how rare they are, until now, using the new survey which looks at hundreds of thousands of galaxies. We found about 3% of galaxies similar to the Milky Way have companion galaxies like the Magellanic Clouds, which is very rare indeed, Robotham said. In total we found 14 galaxy systems that are similar to ours, with two of those being an almost exact match. The Milky Way is locked in a complex cosmic dance with its close companions the Large and Small Magellanic Clouds, which are clearly visible in the southern hemisphere night sky. Many galaxies have smaller galaxies in orbit around them, but few have two that are as large as the Magellanic Clouds. Robotham and his team will continue searching for more Milky Way twin systems.
This image shows one of the two exact matches to the Milky Way system found in a new survey. The larger galaxy, denoted GAMA202627, which is similar to the Milky Way clearly has two large companions off to the bottom left of the image. Credit: Dr Aaron Robotham, ICRAR/St Andrews using GAMA data
ing how hard they are to spot! said Dr. Aaron Robotham with the International Centre for Radio Astronomy Research (ICRAR). Its only recently become possible to do the type of analysis that lets us find similar groups. Everything had to come together at once, Robotham added. We needed telescopes good enough to detect not just galaxies but their faint companions, we needed to look at large sections of the sky, and most of all we needed to make sure no galaxies were missed in the survey. Robotham presented his new findings at the International Astronomical Union General Assembly in Beijing this August, 2012. Using what astronomer consider the most detailed map of the local Universe yet - the Galaxy and Mass Assembly survey (GAMA) - Robotham and his colleagues found that although companions like the Magellanic Clouds are rare, when they are found theyre usually near a galaxy very like the Milky Way, meaning were in just the right place at the right time to have such a great view in our night sky. The galaxy we live in is perfectly typical, but the nearby Magellenic Clouds are a rare, and possibly short-lived, occurrence. We should enjoy them whilst we can, theyll only be around for a few billion more years, said Robotham. Astronomers have used computer simulations of how galaxies form and they dont produce many examples similar to the Milky Way and its surroundings, so they have predicted them to be quite a rare occurrence. Astronomers they really
Light trick to see around corners Scientists have found a novel way to get images through "scattering" materials such as frosted glass or skin, and even to "see around corners". Much research in recent years has focused on correcting for scattering, mostly for medical applications. But the new trick, reported in Nature Photonics, is quick, simple and uses natural light rather than lasers. It uses what is called a spatial light modulator to "undo" the scattering that makes objects opaque or non-reflecting. A camera that can "see around corners" garnered much attention in 2010, using a series of timed laser pulses to illuminate a scene and working out what is around a corner from the timing of the reflections. The prototype device was just one of a great many research efforts trying to crack the problem of scattering. But for some applications, the "time-of-flight" approach that the laser-based camera uses is not sufficient. "If you want to look to see an embryo developing inside an egg but the eggshell scatters everything, or you want to look through the skin, scattering is the main enemy there, and time-of-flight is not a good solution," explained senior author of the study Prof Yaron Silberberg. For those kinds of problems, Prof Silberberg and his colleagues at the Weizmann Institute of Science in Israel have pushed the limits of what spatial light modulators (SLMs) can do. SLMs modify what is known as the phase of an incoming light beam. Like a series of waves on the
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well when the light from an object bounces off a piece of paper; the SLM could "learn" how to undo the paper's scattering effect, making it a nearly perfect reflector. As Prof Silberberg puts it: "You can take a piece of wall and effectively turn it into a mirror, and this is the part that makes everybody raise an eyebrow." However, he said that the primary use for the technique will be in biological and medical studies especially tackling the highly scattering white brain matter in neurological imaging - rather than the business of seeing through thin materials or around corners. "I don't want to say that it solves the problems of secret organisations and Peeping Toms and so on, that's not going to be so simple. But the principle is there. "We have not started to tackle these things... but I see how much interest this raises and think maybe we should." (Source: BBC/Jason Palmer) Worlds Without Suns: Nomad Planets Could Number In The Quadrillions The concept of nomad planets has been featured before here on Universe Today, and for good reason. Not only is the idea of mysterious lone planets drifting sunless through interstellar space an intriguing one, but also the sheer potential quantity of such worlds is simply staggering. If some very well-respected scientists calculations are correct there are more nomad planets in our Milky Way galaxy than there are stars - a lot more. With estimates up to 100,000 nomad planets for every star in the galaxy, there could be literally quadrillions of wandering worlds out there, ranging in size from Pluto-sized to even larger than Jupiter. Thats a lot of nomads. But where did they all come from? Recently, The Kavli Foundation had a discussion with several scientists involved in nomad planet research. Roger D. Blandford, Director of the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) at Stanford University, Dimitar D. Sasselov, Professor of Astronomy at Harvard University and Louis E. Strigari, Research Associate at KIPAC and the SLAC National Accelerator Laboratory talked about their findings and what sort of worlds these nomad planets might be, as well as how they may have formed. One potential source for nomad planets is forceful ejection from solar systems. Most stars form in clusters, and around many stars there are protoplanetary disks of gas and dust in which planets form and then potentially get ejected in various ways, said Strigari. If these early-forming solar systems have a large number
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The letter A with no scattering (top), behind scattering plastic (centre) and re-imaged with the new technique. Credit: Silverburg
ocean that run over rocks or surfers, the waves in light can be slowed down or redirected when they hit scattering materials. SLMs are made up of an array of pixels that can correct for this by selectively slowing down some parts of the beam and allowing others to pass untouched - when an electric field is applied to a pixel, it changes the speed at which light passes through it. Prof Silberberg and his team first set up their SLM by shining light from a normal lamp through a highly scattering plastic film and allowing a computer to finely tune the SLM until they could see a clear image of the lamp through the film. Keeping the SLM set this way, they were then able to obtain clear images of other objects through the film - the SLM effectively turns the film back into a clear sheet. "What we have shown is that you don't need lasers - everybody else was doing this with lasers, and we showed you can do it with incoherent light from a lamp or the Sun - natural light," Prof Silberberg told BBC News. But the team then realised that the same approach can work in reflection - that is, not passing through a scattering material but bouncing off of it, such as the case of light bouncing off a wall at a corner. They then showed the procedure works just as
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There could be quadrillions of nomad planets in our galaxy alone -- and they could even be ejected into intergalactic space. Credit: ESO/S.Brunier
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written about it too, as recently as three weeks ago, and its still a much-debated topic.) In the 20th century, many eminent scientists have entertained the speculation that life propagated either in a directed, random or malicious way throughout the galaxy, said Blandford. One thing that I think modern astronomy might add to that is clear evidence that many galaxies collide and spray material out into intergalactic space. So life can propagate between galaxies too, in principle.
Artist's concept of a free-floating Jupiter-like planet. Credit: NASA/JPL-Caltech
of planets down to the mass of Pluto, you can imagine that exchanges could be frequent. And the possibility of planetary formation outside of stellar disks is not entirely ruled out by the researchers - although they do impose a lower limit to the size of such worlds. Theoretical calculations say that probably the lowest-mass nomad planet that can form by that process is something around the mass of Jupiter, said Strigari. So we dont expect that planets smaller than that are going to form independent of a developing solar system. This is the big mystery that surrounds this new paper. How do these smaller nomad planets form? Sasselov added. Of course, without a sun of their own to supply heat and energy one might assume such worlds would be cold and inhospitable to life. But, as the researchers point out, that may not always be the case. A nomad planets internal heat could supply the necessary energy to fuel the emergence of life or at least keep it going. If you imagine the Earth as it is today becoming a nomad planet life on Earth is not going to cease, said Sasselov. That we know. Its not even speculation at this point. scientists already have identified a large number of microbes and even two types of nematodes that survive entirely on the heat that comes from inside the Earth. Researcher Roger Blandford also suggested that small nomad planets could retain very dense, high-pressure blankets around them. These could conceivably include molecular hydrogen atmospheres or possibly surface ice that would trap a lot of heat. They might be able to keep water liquid, which would be conducive to creating or sustaining life. And so with all these potentially life-sustaining planets knocking about the galaxy is it possible that they could have helped transport organisms from one solar system to another? Its a concept called panspermia, and its been around since at least the 5th century BCE when the Greek philosopher Anaxagoras first wrote about it. (Weve
And so its a very old speculation, but its a perfectly reasonable idea and one that is becoming more accessible to scientific investigation. Nomad planets may not even be limited to the confines of the Milky Way. Given enough of a push, they could be sent out of the galaxy entirely. Just a stellar or black hole encounter within the galaxy can, in principle, give a planet the escape velocity it needs to be ejected from the galaxy. If you look at galaxies at large, collisions between them leads a lot of material being cast out into intergalactic space, Blandford said.
Higgs-like Particle Discovered at CERN Physicists working at the Large Hadron Collider (LHC) have announced the discovery of what they called a Higgs-like boson - a particle that resembles the long sought-after Higgs. We have reached a milestone in our understanding of nature, CERN director general Rolf Heuer told scientists and media at a conference near Geneva on July 4, 2012. The discovery of a particle consistent with the Higgs boson opens the way to more detailed studies, requiring larger statistics, which will pin down the new particles properties, and is likely to shed light on other mysteries of our universe. Two experiments, ATLAS and CMS, presented their preliminary results, and observed a new particle in the mass region around 125-126 GeV, the expected mass range for the Higgs Boson. The results are based on data collected in 2011 and 2012, with the 2012 data still under analysis. The official results will be published later this month and CERN said a more complete picture of todays observations will emerge later this year after the LHC provides the experiments with more data. We observe in our data clear signs of a new particle, at the level of 5 sigma, in the mass region around 126 GeV. The outstanding performance of the LHC and ATLAS and the huge efforts of many people have brought us to this exciting stage, said ATLAS experiment spokesperson Fabiola Gianotti, but a little more time is needed to prepare these results for publication. The discovery of the Higgs is big, in that it is the
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understanding the 96% of the universe that remains obscure. - CERN press release We have reached a milestone in our understanding of nature, said CERN Director General Rolf Heuer. The discovery of a particle consistent with the Higgs boson opens the way to more detailed studies, requiring larger statistics, which will pin down the new particles properties, and is likely to shed light on other mysteries of our universe. Positive identification of the new particles characteristics will take more time and more experiments. But the scientists feel that whatever form the Higgs particle takes, our knowledge of the fundamental structure of matter is about to take a major step forward.
Event recorded with the CMS detector in 2012 at a proton-proton centre of mass energy of 8 TeV. The event shows characteristics expected from the decay of the SM Higgs boson to a pair of photons (dashed yellow lines and green towers). The event could also be due to known standard model background processes. Credit: CERN
last undiscovered piece of the Standard Model that describes the fundamental make-up of the universe. Scientists believe that the Higgs boson, named for Scottish physicist Peter Higgs, who first theorized its existence in 1964, is responsible for particle mass, the amount of matter in a particle. According to the theory, a particle acquires mass through its interaction with the Higgs field, which is believed to pervade all of space and has been compared to molasses that sticks to any particle rolling through it. And so, in theory, the Higgs would be responsible for how particles come together to form matter, and without it, the universe would have remained a formless miss-mash of particles shooting around at the speed of light. Its hard not to get excited by these results, said CERN Research Director Sergio Bertolucci. We stated last year that in 2012 we would either find a new Higgs-like particle or exclude the existence of the Standard Model Higgs. With all the necessary caution, it looks to me that we are at a branching point: the observation of this new particle indicates the path for the future towards a more detailed understanding of what were seeing in the data. A CERN press release says that the next step will be to determine the precise nature of the particle and its significance for our understanding of the universe. Are its properties as expected for the longsought Higgs boson, the final missing ingredient in the Standard Model of particle physics? Or is it something more exotic? The Standard Model describes the fundamental particles from which we, and every visible thing in the universe, are made, and the forces acting between them. All the matter that we can see, however, appears to be no more than about 4% of the total. A more exotic version of the Higgs particle could be a bridge to
Visions of the Cosmos: The Enduring Space Art of David A. Hardy For over 50 years, award-winning space and astronomy artist David A. Hardy has taken us to places we could only dream of visiting. His career started before the first planetary probes blasted off from Earth to travel to destinations in our solar system and before space telescopes viewed distant places in our Universe. It is striking to view his early work and to see how accurately he depicted distant vistas and landscapes, and surely, his paintings of orbiting space stations and bases on the Moon and Mars have inspired generations of hopeful space travellers. Hardy published his first work in 1952 when he was just 15. He has since illustrated and produced covers for dozens of science and science fiction books and magazines. He has written and illustrated his own books and has worked with astronomy and space legends like Patrick Moore, Arthur C. Clarke, Carl Sagan, Wernher von Braun, and Isaac Asimov. His work has been exhibited around the world, including at the National Air & Space Museum in Washington, D.C. which houses two of his paintings. Universe Today is proud to announce that Hardy has helped us update the banner at the top of our website (originally designed by Christopher Sisk) to make it more astronomically accurate. Hardy has also recently debuted his own new website where visitors can peruse and learn more about his work, and buy prints and other items. We had the chance to talk with Hardy about his enduring space art and career: UT: When you first started your space art, there werent images from Voyager, Cassini, Hubble, etc. to give you ideas for planetary surfaces and colored space views. What was your inspiration?
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Top: 'Moon Landing:'' This is one of Hardy's very earliest paintings, done in 1952 when he was just 15. It was also the first to be published. Credit: David A. Hardy. Used by permission. Bottom: 'Skiing on Europe' by David A. Hardy, 1981. Used by permission.
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Top: 'Ferry Rocket and Space Station' by David A. Hardy. Used by permission. Hardys description: A wheel-shaped space station as designed by Wernher von Braun, and a dumbbell-shaped deep-space vehicle designed by Arthur C. Clarke to travel out to Mars and beyond. The only photographs of the Earth from space at this time were a few black-and-white ones from captured German V-2s. Bottom: 'Mars From Deimos' 1956. Credit: David A. Hardy. Used by permission. Hardy's description: 'The dumbell-shaped spaceship (designed by Arthur C. Clarke) shown in the previous 'space station' image has arrived, touching down lightly in the low gravity of Mars's little outer moon, Deimos. The polar cap is clearly visible, and at that time it was still considered possible that the dark areas on Mars were caused by vegetation, fed by the melting caps. On the right of the planet is Phobos, the inner moon.'
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David Hardy: I got to look through a telescope when I was about 16. You only have to see the long shadows creeping across a lunar crater to know that this is a world. But I also found the book The Conquest of Space in my local library, and Chesley Bonestells photographic paintings of the Moon and planets just blew me away! I knew that I wanted to produce pictures that would show people what its really like out there - not just as rather blurry discs of light through a telescope. UT: And now that we have such spacecraft sending back amazing images, how has that changed your art, or how have the space images inspired you? Hardy: I was lucky to start when I did, because in 1957 we had Sputnik, and then the exploration of space really started. We started getting photos of the Earth from space, and of the Moon from probes and orbiters, then of Mars, and eventually from the outer planets. Each of these made it possible to produce better and more realistic and accurate paintings of these worlds. UT: We are amazed at your early work - you were so young and doing such amazing space art! How does it feel to have inspired several generations of people? - Surely your art has driven many to say, I want to go there! Hardy: I certainly hope so - that was the idea! In 1954 I met the astronomer Patrick Moore, who asked me to illustrate a new book in 1954, and we have continued to work together until the present day. Back then we wanted to so a sort of British version of The Conquest of Space, which we called The Challenge of the Stars. In the 1950s we couldnt find a publisher - they all said it was too speculative! But a book with that title was published in 1972; ironically (and unbelievably), just when humans visited the Moon for the last time. We had hoped that the first Moon-landings would lead to a base, and that we would go on to Mars, but for all sorts of reasons (mainly political) this never happened. In 2004 Patrick and I produced a book called Futures: 50 Years in Space, celebrating our 50 years together. It was subtitled: The Challenge of the Stars: What we thought then - What we know now. I quite often find that younger space artists tell me they were influenced by The Challenge of the Stars, just as I was influenced by The Conquest of Space, and this is a great honour. Earth. Through these I have been to the volcanoes of Hawaii and Iceland, to Death Valley CA, the Grand Canyon and Meteor Crater, AZ, to Nicaragua. . . all of these provide not just inspiration but analogues of other worlds like Mars, Io or Triton, so that we can make our work more believable and authentic - as well as more beautiful, hopefully. UT: How has technology changed how you do your work? Hardy: I have always kept up with new technology, making use of xeroxes, photography (I used to do all my own darkroom work and processing), and most recently computers. I got an Atari ST with 512k (yes, K!) of RAM in 1986, and my first Mac in 1991. I use Photoshop daily, but I use hardly any 3D techniques, apart from Terragen to produce basic landscapes and Poser for figures. I do feel that 3D digital techniques can make art more impersonal; it can be difficult or impossible to know who created it! And I still enjoy painting in acrylics, especially large works on which I can use impasto - laying on paint thickly with a palette knife and introducing textures that cannot be produced digitally! UT: Your new website is a joy to peruse - how does technology/the internet help you to share your work? Hardy: Thank you. It is hard now to remember how we used to work when we were limited to sending work by mail, or faxing sketches and so on. The ability to send first a low-res jpeg for approval, and then a high-res one to appear in a book or on a magazine cover, is one of the main advantages, and indeed great joys, of this new technology. UT: I imagine an artist as a person working alone. However, you are part of a group of artists and are involved heavily in the Association of Science Fiction and Fantasy Artists. How helpful is it to have associations with fellow artists? Hardy: It is true that until 1988, when I met other IAAA artists (both US, Canadian and, then, Soviet, including cosmonaut Alexei Leonov) in Iceland I had considered myself something of a lone wolf. So it was almost like coming out of the closet to meet other artists who were on the same wavelength, and could exchange notes, hints and tips. UT: Do you have a favorite image that youve created? Hardy: Usually the last! Which in this case is a commission for a metre-wide painting on canvas called Ice Moon. I put this on Facebook, where it has received around 100 comments and likes - all favourable, Im glad to say. It can be seen there on my page, or on my own website, www.astroart.org
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UT: What places on Earth have most inspired your art? Hardy: Im a past President (and now European VP) of the International Association of Astronomical Artists (IAAA; www.iaaa.org), and we hold workshops in the most alien parts of Planet
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'Antares 2' by David A. Hardy, shows a landscape looking up at the red supergiant star, which we see in Scorpio and is one of the biggest and brightest stars known. It has a small bluish companion, Antares B.
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The Leonids over Stonhenge by David A. Hardy. Used by permission
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'Ice Moon' by David Hardy. Used by permission.
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(UT note: this is a painting in acrylics on stretched canvas, with the description,A blue ice moon of a gas giant, with a derelict spaceship which shouldnt look like a spaceship at first glance.) UT: Anything else you feel is important for people to know about your work? Hardy: I do feel that its quite important for people to understand the difference between astronomical or space art, and SF (sci-fi) or fantasy art. The latter can use a lot more imagination, but often contains very little science - and often gets it quite wrong. I also produce a lot of SF work, which can be seen on my site, and have done around 70 covers for The Magazine of Fantasy & Science Fiction since 1971, and many for Analog. Im Vice President of the Association of Science Fiction & Fantasy Artists (ASFA; www.asfa-art.org) too. But I always make sure that my science is right! I would also like to see space art more widely accepted in art galleries, and in the Art world in general; we do tend to feel marginalised. UT: Thank you for providing Universe Today with a more accurate banner - we really appreciate your contribution to our site! Hardy: My pleasure.
According to a press release from UCLA, astronomers used the sharp eyes of the Hubble Space Telescope to spy on 300 very distant galaxies in the early Universe. The scientists originally thought their galaxy, one of the most massive in their survey going by the unglamorous name of BX442, was an illusion, perhaps two galaxies superimposed on each other. The fact that this galaxy exists is astounding, said David Law, lead author of the study and Dunlap Institute postdoctoral fellow at the University of Torontos Dunlap Institute for Astronomy & Astrophysics. Current wisdom holds that such grand-design spiral galaxies simply didnt exist at such an early time in the history of the universe. A grand design galaxy has prominent, well-formed spiral arms. To understand their image further, astronomers used a unique, state-of-the-art instrument called the OSIRIS spectrograph at the W.M. Keck Observatory atop Hawaiis dormant Mauna Kea volcano. The instrument, built by UCLA professor James Larkin, allowed them to study light from about 3,600 locations in and around BX442. This spectra gave them the clues they needed to show they were indeed looking at a single, rotating spiral galaxy. While spiral galaxies are abundant throughout the current cosmos, that wasnt always the case. Spiral galaxies in the early Universe were rare because of frequent interactions. BX442 looks like a nearby galaxy, but in the early universe, galaxies were colliding together much more frequently, says Shapely. Gas was raining in from the intergalactic medium and feeding stars that were being formed at a much more rapid rate than they are today; black holes grew at a much more rapid rate as well. The universe today is boring compared to this early time.
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Oldest Spiral Galaxy in the Universe Discovered Ancient starlight traveling for 10.7 billion years has brought a surprise - evidence of a spiral galaxy long before other spiral galaxies are known to have formed. As you go back in time to the early universe, galaxies look really strange, clumpy and irregular, not symmetric, said Alice Shapley, a UCLA associate professor of physics and astronomy, and co-author of a study reported in todays journal Nature. The vast majority of old galaxies look like train wrecks. Our first thought was, why is this one so different, and so beautiful? Galaxies today come in a variety of unique shapes and sizes. Some, like our Milky Way Galaxy, are rotating disks of stars and gas called spiral galaxies. Other galaxies, called elliptical galaxies, resemble giant orbs of older reddish stars moving in random directions. Then there are a host of smaller irregular shaped galaxies bound together by gravity but lacking in any visible structure. A great, diverse population of these types of irregular galaxies dominated the early Universe, says Shapely. Light from this incredibly distant spiral galaxy, traveling at nearly six trillion miles per year, took 10.7 billion years to reach Earth; just 3 billion years after the Universe was created in an event called the Big Bang.
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An artists rendering of galaxy BX442 and its companion dwarf galaxy (upper left). Credit: Dunlap Institute for Astronomy & Astrophysics/Joe Bergeron
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These stunning photos of the Aurora Australis and the Milky Way was captured from what may be the coldest and most isolated research facility on Earth: the French-Italian Concordia Base station, located at 3,200 meters (nearly 10,500 feet) altitude on the Antarctic plateau, 1,670 km (1,037 miles) from the geographic south pole. Taken by Dr. Alexander Kumar, a doctor, researcher and photographer whos been living at the Base since January, the image shows the full beauty of the sky above the southern continent - a sky that doesnt see the Sun from May to August.
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Shapely and Law think the gravitational tug-of-war between a dwarf galaxy companion and BX442 may be responsible for its futuristic look. The companion appears as just a small blob in their image. Computer simulations conducted by Charlotte Christensen, a postdoctoral student at the University of Arizona and co-author of the paper, lends evidence to this idea. Eventually, BX442 and the smaller galaxy likely will merge. Shapley said BX442 represents a link between early galaxies that are much more turbulent and the rotating spiral galaxies that we see around us. Indeed, this galaxy may highlight the importance of merger interactions at any cosmic epoch in creating grand design spiral structure, she said. Studying BX442 is likely to help astronomers understand how spiral galaxies like the Milky Way form, she added.
(Source: Universe Today/John WIlliamns)
Aurora and Milky Way over Antarctica We managed to snap a few photos before Heaven realised its mistake and closed its doors. Dr. Alexander Kumar The stunning photos of the Aurora Australis and Milky Way (see previos page), set against a backdrop of the Milky Way, was captured from one of the most remote research locations on the planet: the French-Italian Concordia Base, located located at 3,200 meters (nearly 10,500 feet) altitude on the Antarctic plateau, 1,670 km (1,037 miles) from the geographic south pole. The photos was taken on July 18 by resident doctor and scientist Dr. Alexander Kumar and his colleague Erick Bondoux. Of course, taking photos outside is no easy task. Temperatures outside the Base in winter can drop down to -70C (-100F)! Sparked by a coronal mass ejection emitted from active region 11520 on July 12, Earths aurorae leapt into high gear both in the northern and southern hemispheres three days later during the resulting geomagnetic storm - giving some wonderful views to skywatchers in locations like Alaska, Scotland, New Zealand and even the South Pole. A raw display of one of natures most incredible sights dazzled our crew, Dr. Kumar wrote on his blog, Chronicles from Concordia. The wind died down and life became still. To me, it was if Heaven had opened its windows and a teardrop had fallen from high above our station, breaking the dark lonely polar night. We managed to snap a few photos before Heaven realised its mistake and closed its doors. With winter temperatures as low as -70C (-100F),
no sunlight and no transportation in or out from May to August, Concordia Base is incredibly isolated - so much so that its used for research for missions to Mars, where future explorers will face many of the same challenges and extreme conditions that are found at the Base. But even though they may be isolated, Dr. Kumar and his colleagues are in an excellent location to witness amazing views of the sky, the likes of which are hard to find anywhere else on Earth. Many thanks to them for braving the bitter cold and otherworldly environment to share images like this with us! The dark may cause fear, but if you take the time to adapt and look within it, you never know what you may find - at the bottom of the ocean, in the night sky, or under your bed in the middle of the night, writes Kumar on the Concordia blog. If you dont overcome your fear of the unknown and monsters, you will never see marvellous secrets hidden in the dark. I hope this photo inspires you too for the days, weeks and months ahead. In terms of the space exploration we are only beginning. We have to continue pushing out into the great beyond.
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Nearby Magma Exoplanet is Smaller Than Earth Astronomers have detected what could be one of the smallest exoplanets found so far, just twothirds the size of Earth. And, cosmically speaking, its in our neighborhood, at just 33 light-years away. But this planet, called UCF-1.01, is not a world most Earthlings would enjoy visiting: it likely is covered in magma. We have found strong evidence for a very small,
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were periodic, suggesting a second planet might be orbiting the star and blocking out a small fraction of the stars light. From the data, the astronomers were able to glean some basic properties of this exoplanet: its diameter is approximately 8,400 kilometers (5,200 miles ), or two-thirds that of Earth. UCF-1.01 would revolve quite tightly around its star, GJ 436, at about seven times the distance of Earth from the moon, with its year lasting only 1.4 Earth days. Given this proximity to its star, far closer than the planet Mercury is to our sun, the exoplanets surface temperature would be almost 600 degrees Celsius (about 1,000 degrees Fahrenheit). The planet likely does not have an atmosphere, being so close to the star UCR-1.01s might be a hot lava world. The planet could even be covered in magma, said Joseph Harrington, also of the University of Central Florida and principal investigator of the research. In addition to UCF-1.01, the researchers noticed hints of a third planet, dubbed UCF-1.02, orbiting GJ 436. Spitzer has observed evidence of the two new planets several times each. However, even the most sensitive instruments are unable to measure exoplanet masses as small as UCF-1.01 and UCF-1.02, which are perhaps only one-third the mass of Earth. Knowing the mass is required for confirming a discovery, so the paper authors are cautiously calling both bodies exoplanet candidates for now. Remove this ad While this is Spitzers first potential extra solar planet, the exoplanet-hunting Kepler spacecraft has identified 1,800 stars as candidates for having planetary systems, and just three are verified to contain sub-Earth-sized exoplanets. Of these, only one exoplanet is thought to be smaller than the Spitzer candidates, with a radius similar to Mars, or 57 percent that of Earth. I hope future observations will confirm these exciting results, which show Spitzer may be able to discover exoplanets as small as Mars, said Michael Werner, Spitzer project scientist at NASAs Jet Propulsion Laboratory in Pasadena, Calif. Even after almost nine years in space, Spitzers observations continue to take us in new and important scientific directions.
Caption: This artists concept shows what astronomers believe is an alien world just two-thirds the size of Earth. Credit: NASA/JPL-Caltech
very hot and very near planet with the help of the Spitzer Space Telescope, said Kevin Stevenson from the University of Central Florida in Orlando, lead author of a new paper in The Astrophysical Journal. Identifying nearby small planets such as UCF-1.01 may one day lead to their characterization using future instruments. This is the first time an exoplanet has been found using Spitzer, so astronomers are now rethinking this space telescopes role in helping discover potentially habitable, terrestrial-sized worlds. However, the hot, new-planet candidate was found unexpectedly in Spitzer observations. Stevenson and his colleagues were studying the Neptunesized exoplanet GJ 436b, already known to exist around the red-dwarf star GJ 436. In the Spitzer data, the astronomers noticed slight dips in the amount of infrared light streaming from the star, separate from the dips caused by GJ 436b. A review of Spitzer archival data showed the dips
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Possible Subterranean Life Means More Exoplanets Could Harbor Life When we think of life on other planets, we tend to imagine things (microbes, plant life and yes, humanoids) that exist on the surface. But Earths biosphere doesnt stop at the planets surface, and
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Top:Artistic representation of the current five known potential habitable worlds. Will this list broaden under a new habitability model?; Bottom: Location in the night sky of the stars with potential habitable exoplanets (red circles). There are two in Gliese 581. Click the image for larger version. Credit: The Planetary Habitability Laboratory (PHL)/UPR Arecibo and Jim Cornmell
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neither would life on another world, says a new study that expands the so-called Goldilocks Zone to include the possibility of subterranean habitable zones. This new model of habitability could vastly increase where we could expect to find life, as well as potentially increasing the number of habitable exoplanets. We know that a large fraction of the Earths biomass is dwelling down below, and recently microbiologists discovered bacterial life, 1.4 kilometers below the sea floor in the North Atlantic, deeper in the Earths crust than ever before. This and other drilling projects have brought up evidence of hearty microbes thriving in deep rock sediments. Some derive energy from chemical reactions in rocks and others feed on organic seepage from life on the surface. But most life requires at least some form of water. Life as we know it requires liquid water, said Sean McMahon, a PhD student from the University of Aberdeens (Scotland) School of Geosciences. Traditionally, planets have been considered habitable if they are in the Goldilocks zone. They need to be not too close to their sun but also not too far away for liquid water to persist, rather than boiling or freezing, on the surface. However, we now know that many micro-organisms perhaps half of all living things on Earth reside deep in the rocky crust of the planet, not on the surface. Remove this ad While suns warm planet surfaces, there also heat from the planets interiors. Crust temperature increases with depth so planets that are too cold for liquid water on the surface may be sufficiently warm underground to support life. We have developed a new model to show how Goldilocks zones can be calculated for underground water and hence life, McMahon said. Our model shows that habitable planets could be much more widespread than previously thought. In the past, the Goldilocks zone has really been determined by a circumstellar habitable zone (CHZ), which is a range of distances from a star, and depending on the stars characteristics, the zone varies. The consensus has been that planets that form from Earth-like materials within a stars CHZ are able to maintain liquid water on their surfaces. But McMahon and his professor, John Parnell, also from Aberdeen University who is leading the study now are introducing a new term: subsurfacehabitability zone (SSHZ). This denote the range of distances from a star within which planets are habitable at any depth below their surfaces up to a certain maximum, for example, they mentioned a SSHZ for 2 km depth, within which planets can support liquid water 2 km or less underground. If this notion catches on - which it should - it will have exoplanet hunters recalculating the amount of potentially habitable worlds.
Impossible Binary Star Systems Found Astronomers think about half of the stars in our Milky Way galaxy are, unlike our Sun, part of a binary system where two stars orbit each other. However, theyve also thought there was a limit on how close the two stars could be without merging into one single, bigger star. But now a team of astronomers have discovered four pairs of stars in very tight orbits that were thought to be impossibly close. These newly discovered pairs orbit each other in less than 4 hours. Over the last three decades, observations have shown a large population of stellar binaries, and none of them had an orbital period shorter than 5 hours. Most likely, the stars in these systems were formed close together and have been in orbit around each other from birth onwards. A team of astronomers using the United Kingdom Infrared Telescope (UKIRT) in Hawaii made the first investigation of red dwarf binary systems. Red dwarfs can be up to ten times smaller and a thousand times less luminous than the Sun. Although they form the most common type of star in the Milky Way, red dwarfs do not show up in normal surveys because of their dimness in visible light. But astronomers using UKIRT have been monitoring the brightness of hundreds of thousands of stars, including thousands of red dwarfs, in near-infrared light, using its state-of-theart Wide-Field Camera (WFC). To our complete surprise, we found several red dwarf binaries with orbital periods significantly shorter than the 5 hour cut-off found for Sun-like stars, something previously thought to be impossible, said Bas Nefs from Leiden Observatory in the Netherlands, lead author of the paper which was published in journal Monthly Notices of the Royal Astronomical Society. It means that we have to rethink how these close-in binaries form and evolve. Since stars shrink in size early in their lifetime, the fact that these very tight binaries exist means that their orbits must also have shrunk as well since their birth, otherwise the stars would have been in contact early on and have merged. However, it is not at all clear how these orbits could have shrunk by so much. One possible scenario is that cool stars in binary systems are much more active and violent than previously thought. The astronomers said it is possible that the
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This artists impression shows the tightest of the new record breaking binary systems. Two active M4 type red dwarfs orbit each other every 2.5 hours, as they continue to spiral inwards. Eventually they will coalesce into a single star. Credit: J. Pinfield
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magnetic field lines radiating out from the cool star companions get twisted and deformed as they spiral in towards each other, generating the extra activity through stellar wind, explosive flaring and star spots. Powerful magnetic activity could apply the brakes to these spinning stars, slowing them down so that they move closer together. The active nature of these stars and their apparently powerful magnetic fields has profound implications for the environments around red dwarfs throughout our Galaxy, said team member said David Pinfield from the University of Hertfordshire. UKIRT has a 3.8 meter diameter mirror, and is the second largest dedicated infrared telescope in the world. It sits at an altitude of 4,200 m on the top of the volcano Mauna Kea on the island of Hawaii.
Artist's illustration of Pluto's surface.
Credit: NASA
More Surprises From Pluto Ah, Pluto. Seems every time we think weve got it figured out, it has a new surprise to throw at us. First spotted in 1930 by a young Clyde Tombaugh, for 76 years it enjoyed a comfortable position as the solar systems most distant planet. Then a controversial decision in 2006 by the International Astronomical Union, spurred by suggestions from astronomer (and self-confessed planet-killer) Mike Brown*, relegated Pluto to a new class of worlds called dwarf planets. Not quite planets and not quite asteroids, dwarf planets cannot entirely clear their orbital path with their own gravitational force and thus miss out on full planetary status. Besides immediately making a lot of science textbooks obsolete and rendering the handy mnemonic My Very Eager Mother Just Served Us Nine Pies irrelevant (or at least confusing), the decision angered many people around the world, both in and out of the scientific community. Pluto is a planet, they said, it always has been and always will be! Save Pluto! the schoolkids wrote in crayon to planetarium directors. The world all of a sudden realized how much people liked having Pluto as the last planet, and didnt want to see it demoted by decision, especially a highly contested one. Yet as it turns out, Pluto really may not be a planet after all. It may be a comet. Butthats getting ahead of ourselves. First things first. Recent discoveries by a UK team of astronomers points to the presence of carbon monoxide in Plutos atmosphere. Yes, Pluto has an atmosphere; astronomers have known about it since 1988. At first assumed to be about 100km thick, it was later estimated to extend out about 1500km and be composed of methane gas and
nitrogen. This gas would expand from the planets, dwarf planets - surface as it came closer to the Sun during the course of its eccentric 248-year orbit and then freeze back onto the surface as it moved further away. The new findings from the University of St Andrews team, made by observations with the James Clerk Maxwell telescope in Hawaii, identify an even thicker atmosphere containing carbon monoxide that extends over 3000 km, reaching nearly halfway to Plutos largest moon, Charon. Its possible that this carbon monoxide atmosphere may have expanded outwards from Pluto, especially in the years since 1989 when it made the closest approach to the Sun in its orbit. Surface heating (and the term heating is used scientifically hereremember, at around -240C (400F) Pluto would seem anything but balmy to us!) by the Suns radiation would have warmed the surface and expelled these gases outwards. This also coincides with observations made by the Hubble Space Telescope over the course of four years, which revealed varying patterns of dark and light areas on Plutos surface possibly caused by the thawing of frozen areas that shift and reveal lighter surface material below. Seeing such an example of extra-terrestrial climate-change is fascinating. This cold simple atmosphere that is strongly driven by the heat from the Sun could give us important clues to how some of the basic physics works, and act as a contrasting test-bed to help us better understand the Earths atmosphere. - Dr. Jane Greaves, Team Leader In fact, carbon monoxide may be the key to why Pluto even still has an atmosphere. Unlike methane, which is a greenhouse gas, carbon monoxide acts as a coolant; it may be keeping Plutos fragile atmosphere from heating up too much and escaping into space entirely! Over the decades and centuries that it takes for Pluto to complete a single year, the balance between these
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the many inherent dangers of living and working in space - the Moon itself may be toxic to humans. An international team of researchers has attempted to quantify the health dangers of the Moon - or at least its dust-filled regolith. In a paper titled Toxicity of Lunar Dust (D. Linnarsson et al.) the health hazards of the Moons fine, powdery dust - which plagued Apollo astronauts both in and out of their suits - are investigated in detail (or as best as they can be without actually being on the Moon with the ability to collect pristine samples.) Within their research the team, which included physiologists, pharmacologists, radiologists and toxicologists from 5 countries, investigated some of the following potential health hazards of lunar dust: Inhalation. By far the most harmful effects of lunar dust would come from inhalation of the particulates. Even though lunar explorers would be wearing protective gear, suit-bound dust can easily make its way back into living and working areas as Apollo astronauts quickly discovered. Once inside the lungs the super-fine, sharp-edged lunar dust could cause a slew of health issues, affecting the respiratory and cardiovascular system and causing anything from airway inflammation to increased risks of various cancers. Like pollutants encountered on Earth, such as asbestos and volcanic ash, lunar dust particles are small enough to penetrate deep within lung tissues, and may be made even more dangerous by their long-term exposure to proton and UV radiation. In addition, the research suggests a microgravity environment may only serve to ease the transportation of dust particles throughout the lungs. Skin Damage. Lunar regolith has been found to be very sharp-edged, mainly because it hasnt undergone the same kind of erosive processes that soil on Earth has. Lunar soil particles are sometimes even coated in a glassy shell, the result of rock vaporization by meteorite impacts. Even the finer particles of dust - which constitute about 20% of returned lunar soil samples - are rather sharp, and as such pose a risk of skin irritation in instances of exposure. Of particular note by the research team is abrasive damage to the outer layer of skin at sites of anatomical prominence, i.e., fingers, knuckles, elbows, knees, etc. The dust was so abrasive that it actually wore through three layers of Kevlar-like material on Jack [Schmitt's] boot. - Professor Larry Taylor, Director of the Planetary Geosciences Institute, University of Tennessee (2008) Eye Damage. Needless to say, if particles can pose abrasive damage to human skin, similar danger to the eyes is also a concern. Whether
Artist's impression of Pluto's huge atmosphere of carbon monoxide. The source of this gas is erratic evaporation from the mottled icy surface of the dwarf planet. The Sun appears at the top, as seen in the ultra-violet radiation that is thought to force some of the dramatic atmospheric changes. Pluto's largest moon, Charon, is seen to the lower right. Credit: P.A.S. Cruickshank
two gases must be extremely precise. Actually this is an elaboration of the research results coming from the same team at the University of St Andrews. The additional element here is a tiny redshift detected in the carbon monoxide signature, indicating that it is moving away from us in an unusual way. Its possible that this could be caused by the top layers of Plutos atmosphere - where the carbon monoxide resides being blown back by the solar wind into, literally, a tail. That sounds an awful lot, to this particular astronomy reporter anyway, like a comet. Just saying. Anyway, regardless of what Pluto is or isnt, will be called or used to be called, theres no denying that it is a fascinating little world that deserves our attention. (And it will be getting plenty of that come July 2015 when the New Horizons spacecraft swings by for a visit!) Im sure theres no one here who would argue that fact. New Horizons upcoming visit will surely answer many questions about Pluto - whatever it is - and most likely raise even more.
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The Moon Is Toxic As our closest neighbor in space, a time-capsule of planetary evolution and the only world outside of Earth that humans have stepped foot on, the Moon is an obvious and ever-present location for future exploration by humans. The research that can be done on the Moon - as well as from it - will be invaluable to science. But the only times humans have visited the Moon were during quick, dusty jaunts on its surface, lasting only 2-3 days each before departing. Long-term human exposure to the lunar environment has never been studied in depth, and its quite possible that - in addition to
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Apollo 16 astronaut Charlie Duke with a dust-coated LRV. Side image: a dusty Gene Cernan in the LM at the end of an Apollo 17 EVA.
Credit: NASA/JSC
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lunar dust makes its way into the eye via airborne movement (again, much more of a concern in microgravity) or through direct contact from fingers or another dust-coated object, the result is the same: danger of abrasion. Having a scratched cornea is no fun, but if youre busy working on the Moon at the time it could turn into a real emergency. While the research behind the paper used data about airborne pollutants known to exist on Earth and simulated lunar dust particles, actual lunar dust is harder to test. The samples returned by the Apollo missions have not been kept in a true lunarlike environment - being removed from exposure to radiation and not stored in a vacuum, for instance and as such may not accurately exhibit the properties of actual dust as it would be encountered on the Moon. The researchers conclude that only studies conducted on-site will fill the gaps in our knowledge of lunar dust toxicity. Still, the research is a step in the right direction as it looks to ensure a safe environment for future explorers on the Moon, our familiar - yet still alien satellite world. (Source: Universe Today/Jason Major) NASA To Launch The Finest Mirrors Ever Made This Wednesday NASA will launch its High Resolution Coronal Imager (HI-C) mission from White Sands Missile Range in New Mexico, sending a sounding rocket above the atmosphere with some of the best mirrors ever made to capture incredibly-detailed ultraviolet images of our Sun. HI-C will use a state-of-the-art imaging system to focus on a region near the center of the Sun about 135,000 miles (271,000 km) across. During its brief flight - only ten minutes long - HI-C will return some of the most detailed images of the Suns corona ever acquired, with a resolution five times that of previous telescopes including NASAs Solar Dynamics Observatory. While SDO collects images in ten wavelengths, however, HI-C will focus on just one: 193 Angstroms, a wavelength of ultraviolet radiation that best reveals the structures of the Suns corona present in temperatures of 1.5 million kelvin. And although HI-Cs mirrors arent any larger than SDOs - about 9.5 inches in diameter - they are some of the finest ever made. In addition, an interior maze between mirrors effectively increases HI-Cs focal length.
A Black Brant sounding rocket containing NASAs HI-C mission will launch on July 11, 2012 to observe the suns corona. (NASA) Bottom image: TRACE image of the Sun at a resolution of 0.5 arcsec/pixel. HI-C will have a resolution 5 times finer. Credit: NASA
given pixel - that structures in the suns atmosphere are about 100 miles across, said Jonathan Cirtain, project scientist for HI-C at NASAs Marshall Space Flight Center. And we also have theories about the shapes of structures in the atmosphere, or corona, that expect that size. HI-C will be the first chance we have to see them. One of the main goals of HI-C will be to place significant new constraints on theories of coronal heating and structuring, by observing the smallscale processes that exist everywhere in hot magnetized coronal plasma and establishing whether or not there are additional structures below what can currently be seen. This instrument could push the limits on theories of coronal heating, answering questions such as why the temperature of the suns corona is millions of degrees higher than that of the surface, said Marshalls Dr. Jonathan Cirtain, heliophysicist and principle investigator on the mission.
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Researchers expect HI-Cs super-smooth mirrors to resolve coronal structures as small as 100 miles (160 km) across (0.1 arcsec/pixel). Other instruments in space cant resolve things that small, but they do suggest - after detailed computer analysis of the amount of light in any
Space Junk: Ideas for Cleaning up Earth Orbit Space may be big - vastly, hugely, mind-bogglingly big - but the space around Earth is beginning to get cluttered with space junk. This poses a threat, not only to other satellites, space stations and missions, but to us here on Earth as well. While we wrestle with environmental issues posed by human activity on our planet, ESAs new Clean Space initiative aims to address the same issues for its missions, making them greener by using more
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operation. The rest are derelict and liable to fragment as leftover fuel or batteries explode. Traveling at around 7.5 km/s, a 2 cm screw has a lethal diameter sufficient to take out a satellite. Taking the recent loss of the Envisat satellite as an example, this satellite now poses a considerable threat as space junk. An analysis of space debris at Envisats orbit suggests there is a 15% to 30% chance of collision with another piece of junk during the 150 years it is thought Envisat could remain in orbit. The satellites complexity and size means even a small piece of debris could cause a fragmentation event producing its own population of space garbage. Envisat is also too big to be allowed to drift back into the Earths atmosphere. The choices seem to be to raise the satellite to a higher, unused orbit, or guide it back in over the Pacific Ocean. As ESA Director General Jean-Jacques Dordain says We will not succeed alone; we will need everyones help. The entire space sector has to be with us. (Source: Universe Today/Jenny Winder) Rethinking the Source of Earths Water Earth, with its blue hue visible from space, is known for its abundant water - predominately locked in oceans - that may have come from an extraterrestrial source. New research indicates that the source of Earths water isnt from ice-rich comets, but instead from water-bearing asteroids. Looking at the ratio of hydrogen to deuterium, a heavy isotope of hydrogen, in frozen water, scientists can get a pretty good idea of the distance the water formed in the solar system. Comets and asteroids farther from the Sun have a higher deuterium content than ice formed closer to the Sun. Scientists, led by the Carnegie Institution for Sciences Conel Alexander, compared water from comets and from carbonaceous chondrites. What they found challenges current models in how the solar system formed. Primeval Earth was a hot and dry place. Any water that may have formed with Earth was boiled away from the scorching crust. Ultraviolet light from the newly formed Sun stripped hydrogen atoms from the water molecules leaving no rain to fall back on the surface. Scientists believe that both comets and carbonaceous asteroids formed beyond the orbit of Jupiter, perhaps at the very fringes of the solar system, then moved inward bringing both water and organic material to Earth. If this were true, Alexander and his colleagues suggest that ice found in comets and the remnants of ice preserved in carbonaceous chondrites in the form of clays would have similar isotopic composition. After studying 85 carbonaceous chondrites, supplied by Johnson Space Center and the Meteorite Working Group, they show in a paper
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Artists impression of debris in low earth orbit
Credit: ESA
eco-friendly materials and finding ways to cut down levels of space debris. Last month ESA and Eurospace organized the Clean Space Eco-design and Green Technologies Workshop 2012 held in the Netherlands. Clean Space is a major objective of Agenda 2015, the Agencys upcoming action plan. The aim was outlined by ESA Director General Jean-Jacques Dordain: If we are convinced that space infrastructure will become more and more essential, then we must transmit the space environment to future generations as we found it, that is, pristine. The workshop looked at all aspects of space missions, their total environment impact, from concept development to end of life. The impact of regulations regarding substances such as hydrazine, which is used widely as a propellant in space programs and the development of Green Propulsion with propellants that have a reduced toxicity. Environmental friendliness and sustainability often mean increased efficiency, which ESA hopes will give the industry a competitive advantage, so they are looking at technologies which will consume less energy and produce less waste, therefore cutting costs. Finally they looked at debris mitigation to minimize the impact to the space environment as well as the debris footprint on Earth using controlled and uncontrolled re-entry events and passive deorbiting systems along with active de-orbiting and re-orbiting systems. They are even considering tethers or sails to help drag abandoned satellites out of low orbit within 25 years. New design for demise concepts hope to prevent chunks of satellites surviving re-entry and hitting the ground intact. Active removal of existing debris is also needed, including robotic missions to repair or deorbit satellites. 6,000 satellites have been launched during the Space Age; less than 1000 of these are still in
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massive filament that stretched across 18 megaparsecs (nearly 59 million light-years) of space. The alignment of the string enhanced the lensing effect. The teams results were published in the July 4, 2012 issue of Nature. It looks like theres a bridge that shows that there is additional mass beyond what the clusters contain, Dietrich said in a press release. The clusters alone cannot explain this additional mass. By examining X-rays emanating from plasma in the filament, observed from the XMM-Newton satellite, the team calculated that no more than nine percent of the filaments mass could be made up of the hot gas. Computer simulations further suggested that just 10 percent of the mass was due to visible stars and galaxies. Only dark matter, says Dietrich, could make up the remaining mass. Whats exciting, says Mark Bautz, an astrophysicist at the Massachusetts Institute of Technology, is that in this unusual system we can map both dark matter and visible matter together and try to figure out how they connect and evolve along the filament. Refining the technique could help physicists understand the structure of the Universe and pin
Artist impression of an asteroid impact on early Earth.
Credit: NASA
released today by Science Express that they likely did not form in the same regions of the solar system as comets because they have much lower deuterium content. They formed closer to the Sun, perhaps in the asteroid belt between Mars and Jupiter. And its that material that rained on early Earth to create the wet planet we know today. Our results provide important new constraints for the origin of volatiles in the inner solar system, including the Earth, Alexander said. And they have important implications for the current models of the formation and orbital evolution of the planets and smaller objects in our solar system.
(Source: Universe Today/John Williams)
Dark Matter Filaments Bind Galaxies Together A slim bridge of dark matter - just a hint of a larger cosmic skeleton - has been found binding a pair of distant galaxies together. According to a press release from the journal Nature, scientists have traced a thread-like structure resembling a cosmic web for decades but this is the first time observations confirming that structure has been seen. Current theory suggests that stars and galaxies trace a cosmic web across the Universe which was originally laid out by dark matter a mysterious, invisible substance thought to account for more than 80 percent of the matter in the Universe. Dark matter can only be sensed through its gravitational tug and only glimpsed when it warps the light of distant galaxies. Astronomers led by Jrg Dietrich, a physics research fellow in the University of Michigan College of Literature, Science and the Arts, took advantage of this effect by studying the gravitational lensing of galactic clusters Abell 222 and 223. By studying the light of tens of thousands of galaxies beyond the supercluster; located about 2.2 billion light-years from Earth, the scientists were able to plot the distortion caused by the Abell cluster. The scientists admit it is extremely difficult to observe gravitational lensing by dark matter in the filaments because they contain little mass. Their workaround was to study a particularly
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Dark-matter filaments, such as the one bridging the galaxy clusters Abell 222 and Abell 223, are predicted to contain more than half of all matter in the Universe. Credit: Jrg Dietrich, Univ. of Michigan/Univ. Observatory Munich
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down the identity of dark matter (whether its a cold slow-moving mass or a warm, fast-moving one. Different types would clump differently along the filament, say scientists. Dark Galaxies Found from the Early Universe How do you find a dark galaxy? Shine some light on the subject. Dark galaxies - ancient galaxies that contain little to no stars - have been theorized to exist but have not been observed, until now. An international team of astronomers think they have detected these elusive objects by observing them glowing as they are illuminated by a quasar. Dark galaxies are small, gas-rich galaxies in the early Universe that are very inefficient at forming stars. They are predicted by theories of galaxy formation and are thought to be the building blocks of todays bright, star-filled galaxies. Astronomers think that they may have fed large galaxies with much of the gas that later formed into the stars that exist today. Being essentially devoid of stars, these dark galaxies dont emit much light, making them very hard to detect. For years astronomers have been trying to develop new techniques that could confirm the existence of these galaxies. Small absorption dips in the spectra of background sources of light have hinted at their existence. However, this new study marks the first time that such objects have been seen directly. Our approach to the problem of detecting a dark galaxy was simply to shine a bright light on it, said Simon Lilly, from the Institute for Astronomy at ETH Zurich, Switzerland) co-author of a new paper published in the Monthly Notices of the Royal Astronomical Society. We searched for the fluorescent glow of the gas in dark galaxies when they are illuminated by the ultraviolet light from a nearby and very bright quasar. The light from the quasar makes the dark galaxies light up in a process similar to how white clothes are illuminated by ultraviolet lamps in a night club. Fluorescence is the emission of light by a substance illuminated by a light source. Quasars are very bright, distant galaxies, and their brightness makes them powerful beacons that can help to illuminate the surrounding area, probing the era when the first stars and galaxies were forming out of primordial gas. In order to detect the extremely faint fluorescent glow of these dark galaxies, the team used the Very Large Telescope (VLT), and took a series of very long exposures, mapping a region of the sky around the bright quasar HE 0109-3518. They looked for the ultraviolet light that is emitted by hydrogen gas when it is subjected to intense radiation.
This deep image shows the region of the sky around the quasar HE01093518, near the center of the image. The energetic radiation of the quasar makes dark galaxies glow, helping astronomers to understand the obscure early stages of galaxy formation. Credit: ESO, Digitized Sky Survey 2 and S. Cantalupo (UCSC)
The team detected almost 100 gaseous objects lying within a few million light-years of the quasar, and narrowed the possible dark galaxies down to 12 objects. The team says these are the most convincing identifications of dark galaxies in the early Universe to date. Our observations with the VLT have provided evidence for the existence of compact and isolated dark clouds, said Sebastiano Cantalupo from the University of California, Santa Cruz, lead author of the paper. With this study, weve made a crucial step towards revealing and understanding the obscure early stages of galaxy formation and how galaxies acquired their gas. The astronomers were also able to determine some of the properties of the dark galaxies, and estimate that the mass of the gas in them is about 1 billion times that of the Sun, typical for gas-rich, low-mass galaxies in the early Universe. They were also able to estimate that the star formation efficiency is suppressed by a factor of more than 100 relative to typical star-forming galaxies found at similar stage in cosmic history.
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The Return of the Rings! Now that Cassini has gone off on a new trajectory taking it above and below the equatorial plane of Saturn, were back to getting some fantastic views of the rings - the likes of which havent been seen in over two and a half years! The next image shows portions of the thin, ropy F ring and the outer A ring, which is split by the
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Credit: NASA/JPL/Space Science Institute
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Credit: NASA/JPL/Space Science Institute
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202-mile (325-km) -wide Encke gap. The shepherd moon Pan can be seen cruising along in the gap along with several thin ringlets. Near the A rings outer edge is a narrower space called the Keeler gap - this is the home of the smaller shepherd moon Daphnis, which isnt visible here (but is one of my personal favorites!) The scalloped pattern on the inner edge of the Encke gap downstream from Pan and a spiral pattern moving inwards from that edge are created by the 12.5-mile-wide (20-km-wide) moons gravitational influence. Other features that have returned for an encore performance are the so-called propellers, spiral sprays of icy ring material created by tiny micromoons within the rings. Individually too small to discern (less than half a mile in diameter) these propeller moons kick up large clumps of reflective ring particles with their gravity as they travel through the rings, revealing their positions. The two images above show a propeller within the A ring. Nicknamed Sikorsky after RussianAmerican aviator Igor Sikorsky, the entire structure is about 30 miles (50 km) across and is one of the more well-studied propellers. Scientists are eager to understand the interactions of propellers in Saturns rings as they may hold a key to the evolution of similar systems, such as solar systems forming from disks of matter. See a video of a propeller orbiting within the rings here, and heres an image of one thats large enough to cast a shadow! One of the main contributing factors to the enormous success we on the Cassini mission have enjoyed in the exploration of Saturn is the capability to view the planet and the bodies around it from a variety of directions, Cassini Imaging Team Leader Carolyn Porco wrote earlier today. Setting the spacecraft high into orbit above Saturns equator provides us direct views of the equatorial and middle latitudes on the planet and its moons, while guiding it to high inclination above the equator plane affords the opportunity to view the polar regions of these bodies and be treated to vertigo-inducing shots of the planets glorious rings. (Source: Universe Today/Nancy Atkinson) Planets Found in a Cluster of Buzzing Stars Theres a classic science fiction story called Nightfall, written by the late-great Isaac Asimov. Its the tale of a world with six suns that fill the sky with such brightness that the inhabitants have no concept of night. And then one day, a once-in-athousand-years alignment causes all the stars to set at once; and everyone goes crazy! In another case of science following science fiction, NASA-funded astronomers have discovered
Artist's illustration of a planet within a cluster. Credit: NASA/JPL-Caltech
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planets orbiting within a dense cluster of stars called the Beehive Cluster; a collection of 1,000 stars collected around a common center of gravity - Nightfall worlds?! Well, not so fast. These worlds are hot Jupiters; massive, boiling hot planets that orbit their parent star closer than Mercury in our own Solar System. The two new planets have been designated Pr0201b and Pr0211b after Praesepe, another name for the Beehive Cluster. Although they arent habitable, the view from those planets in a dense cluster of stars would be awe inspiring, with hundreds of stars within a radius of 12 light-years. Astronomers had long predicted that planets should be common in star clusters. Consider that our own Solar System probably formed within a star forming complex like the Orion Nebula. Then the individual stars drifted away from each other over time, taking their planets with them. The evolution of the Beehive cluster was different, though, with the mutual gravity of the 1,000+ stars holding themselves together over hundreds of millions of years. We are detecting more and more planets that can thrive in diverse and extreme environments like these nearby clusters, said Mario R. Perez, the NASA astrophysics program scientist in the Origins of Solar Systems Program. Our galaxy contains more than 1,000 of these open clusters, which
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Early Galaxy Found from the Cosmic Dark Ages Take a close look at the pixelated red spot on the lower right portion of the image above, as it might be the oldest thing humanity has ever seen. This is a galaxy from the very early days of the Universe, and the light from the primordial galaxy traveled approximately 13.2 billion light-years before reaching the Spitzer and Hubble space telescopes. The telescopes - and the astronomers using them had a little help from a gravitational lens effect to be able to see such a faint and distant object, which was shining way back when our Universe was just 500 million years old. This galaxy is the most distant object we have ever observed with high confidence, said Wei Zheng, a principal research scientist in the department of physics and astronomy at Johns Hopkins University in Baltimore who is lead author of a new paper appearing in Nature. Future work involving this galaxy, as well as others like it that we hope to find, will allow us to study the universes earliest objects and how the dark ages ended. This ancient and distant galaxy comes from an important time in the Universes history - one which astronomers know little about - the early part of the epoch of reionization, when the Universe began to move from the so-called cosmic dark ages. During this period, the Universe went from a dark, starless expanse to a recognizable cosmos full of galaxies. The discovery of the faint, small galaxy opens a window onto the deepest, most remote epochs of cosmic history. In essence, during the epoch of reionization, the lights came on in the universe, said paper coauthor Leonidas Moustakas, from JPL. Because both the Hubble and Spitzer telescopes were used in this observation, this newfound galaxy, named MACS 1149-JD, was imaged in five different wavebands. As part of the Cluster Lensing And Supernova Survey with Hubble Program, the Hubble Space Telescope registered the newly described, far-flung galaxy in four visible and infrared wavelength bands. Spitzer measured it in a fifth, longer-wavelength infrared band, placing the discovery on firmer ground. Objects at these extreme distances are mostly beyond the detection sensitivity of todays largest telescopes. To catch sight of these early, distant galaxies, astronomers rely on gravitational lensing, where the gravity of foreground objects warps and magnifies the light from background objects. A massive galaxy cluster situated between our galaxy and MACS 1149-JD magnified the newfound galaxys light, brightening the remote object some 15 times and bringing it into view.
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Beehive Cluster. Credit: Tom Bash and John Fox/Adam Block/NOAO/AURA/NSF
potentially can present the physical conditions for harboring many more of these giant planets. Until now, only two planets had been uncovered around massive stars in star clusters, but none around sun-like stars within these clusters. So the possibility of life was out of the question. These super-jupiters arent habitable either, but its possible that smaller planets will turn up in time as well. The planets were discovered by using the 1.5meter Tillinghast telescope at the Smithsonian Astrophysical Observatorys Fred Lawrence Whipple Observatory near Amado, Arizona to measure the slight gravitational wobble the orbiting planets induce upon their host stars. This discovery might help astronomers with another mystery that has been puzzling them for a few years: how can hot Jupiters form? How can a massive planet form so close to their parent star? Instead of forming close, its possible that the constant gravitational interactions among stars in young clusters push planets back and forth. Some are spun out into space as rogue planets, while others spiral inward and settle into these tight orbits. Could there be life on Earth-sized worlds within these clusters? Are there civilizations out there who have never known the concept of night? Probably not. According to other researchers who released their findings just a week before the Tillinghast study, planets within star clusters like the Beehive probably arent habitable. In a paper titled, Can habitable planets form in clustered environments?, a team of European astronomers considered the environmental effects of star clusters on the formation and evolution of planetary systems. According to their simulations, there are just too many dynamic gravitational encounters with other stars in the cluster for any planet to remain long in the habitable zone.
(Source: Universe Today/Fraser Cain)
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In the big image at left, the many galaxies of a massive cluster called MACS J1149+2223 dominate the scene. Gravitational lensing by the giant cluster brightened the light from the newfound galaxy, known as MACS 1149-JD, some 15 times. At upper right, a partial zoom-in shows MACS 1149-JD in more detail, and a deeper zoom appears to the lower right. Credit: NASA/ESA/STScI/JHU
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Astronomers use redshift to describe cosmic distances, and the ancient but newly-found galaxy has a redshift, of 9.6. The term redshift refers to how much an objects light has shifted into longer wavelengths as a result of the expansion of the universe. Based on the Hubble and Spitzer observations, astronomers think the distant galaxy was less than 200 million years old when it was viewed. It also is small and compact, containing only about 1 percent of the Milky Ways mass. According to leading cosmological theories, the first galaxies indeed should have started out tiny. They then progressively merged, eventually accumulating into the sizable galaxies of the more modern universe. The epoch of reionization refers to the period in the history of the Universe during which the predominantly neutral intergalactic medium was ionized by the emergence of the first luminous sources, and these first galaxies likely played the dominant role in lighting up the Universe. By studying reionization, astronomers can learn about the process of structure formation in the Universe, and find the evolutionary links between the smooth matter distribution at early times revealed by cosmic microwave background studies, and the highly structured Universe of galaxies and clusters of galaxies at redshifts of 6 and below. This epoch began about 400,000 years after the Big Bang when neutral hydrogen gas formed from cooling particles. The first luminous stars and their host galaxies emerged a few hundred million years later. The energy released by these earliest galaxies is thought to have caused the neutral hydrogen strewn throughout the Universe to ionize, or lose an electron, a state that the gas has remained in since that time.
A simulation of the Eltanin strike.
Researchers examining sediments in the area discovered tiny grains of impact melt and debris from meteorite fragments. Something big smashed this spot. An asteroid strike on land is devastating, but an asteroid strike in the deep ocean is even worse. On both land and ocean, you get the plume of water vapor, sulfur, and dust blasted into the high atmosphere, raining molten rock down across a wide area. But for asteroid strikes in the ocean, this is followed by a devastating tsunami that inundates coastlines around the world. There are waves hundreds of meters high at the crash site, and they travel deep inland on every coastline. A local event becomes a global event. But with the Eltanin meteor, this was followed by a prolonged ice age. Professor James Goff and his colleagues from the University of New South Wales in Australia have been researching the Eltanin meteor and its aftereffects. The timing of the impact seems to line up with geologic deposits in Chile, Australia and Antarctica. Geologists traditionally connected these deposits with slower geological processes, like glaciation. But Goff and his team think these deposits might have been dropped all at once by the devastating tsunami from Eltanin. Heres a video that shows how the impact and subsequent tsunami might have played out. Although the Earth was already thought to be cooling in the mid to late Pliocene, the material kicked into the high atmosphere by Eltanin could have pushed the planets climate past the tipping point: Theres no doubt the world was already cooling through the mid and late Pliocene, says co-author Professor Mike Archer. What were suggesting is that the Eltanin impact may have rammed this slow-moving change forward in an instant - hurtling the world into the cycle of glaciations that characterized the next 2.5 million years and tigge-
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Did a Killer Asteroid Drive the Planet Into An Ice Age? When a mountain-sized asteroid struck the deep ocean off the coast of Antarctica 2.5 million years ago, it set off an apocalyptic chain of events: a devastating rain of molten rock and then a deadly tsunami that inundated the coastlines of the Pacific Ocean. But according to a team of Australian researchers, this was just the beginning. Then came a protracted ice age that killed off many of the Earths large mammals. The Eltanin meteor, named after the USNS Eltanin which surveyed the area in 1964, is the only impact that has ever been discovered in a deepocean basin. These deep water impacts must be more common so much of the planet is ocean but theyre tricky to find because of the inaccessible depths of the impact craters.
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red our own evolution as a species. It was this time of a global ice age that transitioned the planet from the Pliocene to the Pleistocene. It was a bad time to be a Chalicothere or Anthracotheriidae, but a good time to be a hominid. So thanks Eltanin. that a singularity can be more subtle where just a patch of spacetime cannot be made to look locally flat in any coordinate system. Locally flat refers to space that appears to be flat from a certain perspective. Our view of the Earth from the surface is a good example. Earth looks flat to a sailor in the middle of the ocean. Its only when we move far from the surface that the curvature of the Earth becomes apparent. Einsteins theory of general relativity begins with the assumption that spacetime is also locally flat. Shockwaves create an abrupt change, or discontinuity, in the pressure and density of a fluid. This creates a jump in the curvature of spacetime but not enough to create the crinkling seen in the teams models, Temple says. The coolest part of the finding for Temple is that everything, his earlier work on shockwaves during the Big Bang and the combination of Voglers and Reintjes work, fits together. There is so much serendipity, says Temple. This is really the coolest part to me. I like that it is so subtle. And I like that the mathematical field of shockwave theory, created to address problems that had nothing to do with General Relativity, has led us to the discovery of a new kind of spacetime singularity. I think this is a very rare thing, and Id call it a once in a generation discovery. While the model looks good on paper, Temple and his team wonder how the steep gradients in spacetime at a regularity singularity could cause larger than expected effects in the real world. General relativity predicts gravity waves might be produced by the collision of massive objects, such as black holes. We wonder whether an exploding stellar shock wave hitting an imploding shock at the leading edge of a collapse, might stimulate stronger than expected gravity waves, Temple says. This cannot happen in spherical symmetry, which our theorem assumes, but in principle it could happen if the symmetry were slightly broken. (Source: Universe Today/John Williams) SETI Astronomer Jill Tarter Recalls Contact, 15 Years On In 1985, famed astronomer, author and TV host Carl Sagan invited Jill Tarter to dinner at his house near Cornell University. Tarter, heavily involved with the Search for Extra-Terrestrial Intelligence, gladly accepted the chance to speak with Sagan, a member of SETIs board of trustees. Seated with Sagan and his wife, Ann Druyan, Tarter learned that Sagan had a fiction book on the go. Annie said, You may recognize someone in the book, but I think youll like her, Tarter recalled in an interview with Universe Today.
(Source: Universe Today/Fraser Cain)
A Crinkle in the Wrinkle of Space-time Albert Einsteins revolutionary general theory of relativity describes gravity as a curvature in the fabric of spacetime. Mathematicians at University of California, Davis have come up with a new way to crinkle that fabric while pondering shockwaves. We show that spacetime cannot be locally flat at a point where two shockwaves collide, says Blake Temple, professor of mathematics at UC Davis. This is a new kind of singularity in general relativity. Temple and his collaborators study the mathematics of how shockwaves in a perfect fluid affect the curvature of spacetime. Their new models prove that singularities appear at the points where shock waves collide. Voglers mathematical models simulated two shockwaves colliding. Reintjes followed up with an analysis of the equations that describe what happens when the shockwaves cross. He dubbed the singularity created a regularity singularity. What is surprising, Temple told Universe Today, is that something as mundane as the interaction of waves could cause something as extreme as a spacetime singularity - albeit a very mild new kind of singularity. Also surprising is that they form in the most fundamental equations of Einsteins theory of general relativity, the equations for a perfect fluid. The results are reported in two papers by Temple with graduate students Moritz Reintjes and Zeke Vogler in the journal Proceedings of the Royal Society A. Einstein revolutionized modern physics with his general theory of relativity published in 1916. The theory in short describes space as a fourdimensional fabric that can be warped by energy and the flow of energy. Gravity shows itself as a curvature of this fabric. The theory begins with the assumption that spacetime (a 4-dimensional surface, not 2 dimensional like a sphere), is also locally flat, Temple explains. Reintjes theorem proves that at the point of shockwave interaction, it [spacetime] is too crinkled to be locally flat. We commonly think of a black hole as being a singularity which it is. But this is only part of the explanation. Inside a black hole, the curvature of spacetime becomes so steep and extreme that no energy, not even light, can escape. Temple says
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Artist rendition of the unfurling of spacetime at the beginning of the Big Bang. Credit: John Williams/TerraZoom
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From her point of view, she was clear she wasnt going to teach anyone astronomy. She was interested, in a personal way, about what the scientists were like, Tarter said. When the crew was filming at the Arecibo Observatory in Puerto Rico, Tarter flew there to observe the work, meet with Foster and also show the actress around. Tarter recalls bringing Foster up in a cabin that had a perfect view of the telescope, some 500 feet above the dish. Microphones and walkie-talkies Filming was an interesting process for Tarter, as well. There were the microphones, and the tools the crew used to check continuity. Most amusingly for Tarter, she observed Foster (reported height 5 feet, 2 inches) needing to stand on a box for most of the close-up shots with actor Matthew McConaughey (reported as 6 feet tall). Two errors still irk Tarter today. There is a scene when Ellie gives a modified version of the Drake Equation, which calculates the odds of intelligent life who are capable of communicating with other life forms, and the calculations are all wrong. Its really infuriating, Tarter said. The other large mistake is a scene where Ellie gets a potential signal from space, while working at the Karl G. Jansky Very Large Array set of radio telescopes in New Mexico. Shes sitting in the middle of the array, in a car, with her laptop, and she gets the signal. And the first thing she does is pick up a walkie-talkie and start broadcasting. That signal is going to wipe out the signal from the sky. You dont transmit by walkie-talkie. But overall, Tarter said the movie did a great job at portraying the feel of SETI. And Foster appreciated Tarters help. She would write me handwritten thank-you notes, which was a kind of manner that most people have lost. A great courtesy. Hollywood outreach Tarter walked the red carpet at the movie premiere and spent most of her time watching the film in tears of happiness. That euphoria evaporated when she saw the SETI Institute was not credited at the end of the film. When she talked to one of the film producers, she said she was informed that lawyers usually draft agreements specifying the length of time the credit appears, and the compensation received for doing so. We dont have a lawyer at the SETI Institute, she said. When I write a paper, I acknowledge my collaborators. We got that wrong, so we never got any credit. We might have gotten even more recognition. But the professional connection with Foster still remains. Foster happily responded to a request
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SETIs Jill Tarter.
Credit: SETI
Suspecting the character was based on herself, Tarters response to Druyan was: Just make sure she doesnt eat ice cones so much. It was something I was teased about. Female, in a male-dominated field It was 15 years ago this month that the movie Contact, based on Sagans book of the same title, expanded to a run in international theatres after a successful summer in North America. The movie explores the implication of aliens making contact with Earth, but does it from more of a scientific perspective than most films. While Contact, the movie did not talk about the pi sequences or advanced mathematical discussions in Contact, the book, it did bring concepts such as prime numbers, interference with radio telescopes, and the religion vs. science debate to theatres in 1997. Tarter, who has just retired as the long-time director of the SETI Institute, said she was stunned by the parallels between her own life and that of Ellie Arroway, the character based on her in Contact. Both lost parents at an early age. Both also had to make their way in a field aggressively dominated by males. Tarter recalls a meeting with fellow female scientists of her generation some years ago. A huge percentage of us had been, in high school, either cheerleaders or drum majorettes. This is so counterintuitive, right? Because were the nerds, were the brainy ones (it was because) we were all competitors, and there werent any (female) sports to compete at. These sports were open, and we competed, and we generally won. Working on set Tarter cautions the parallels did not totally match. The hopes and aspirations of Ellie in the book, and also the movie, were products of Sagans imagination. But the producers and actors of the film did want to get a close sense of what it was like to work with SETI. After Jodie Foster was cast as Ellie, there were multiple phone calls between the actress and Tarter to discuss SETI.
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Solar shockwaves would have produced proto-planetary rings at different times, meaning the planets did not form simultaneously (artist concept). Credit: ESO
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from Tarter to do voice-overs for a video clip used for a SETI high school curriculum for integrated science. She also narrated a show, Life: A Cosmic Story, for the California Academy of Sciences Morrison Planetarium. Tarter is now shifting into full-time outreach for SETI, saying the budgetary problems that shut down the organizations Allen Telescope Array for several months last year were a warning call. One of the organizations newest initiatives is SETILive.org, which crowdsources analysis of signals from the Kepler Field. SETI solicits the public to take some time looking at the signal patterns, one at a time, in search of extraterrestrial communications. SETI is too important to allow it to fail, Tarter said, adding her focus is finding substantial, stable funding from that individual or institution that is capable of taking a long view. another half a million years on we would see the very early stages of Mercury, Venus, Earth and Mars. The shockwaves emitted from the new-born Sun would have rippled out material at different times, creating a series of debris rings around the Sun from which the planets formed. Abdylmayanov hopes that this research will help us understand the development of planets around distant stars. Studying the brightness of stars that are in the process of forming could give indications as to the intensity of stellar shockwaves. In this way we may be able to predict the location of planets around far-flung stars millions of years before they have formed.
(Source: Universe Today/Elizabeth Howell)
Planets in our Solar System May Have Formed in Fits and Starts Did all the planets in our Solar System form at about the same time? Conventional thinking says the components of our Solar System all formed at the same time, and formed rather quickly. But new research indicates that a series of shockwaves emitted from our very young Sun may have caused the planets to form at different times over millions of years. The planets formed in intervals - not altogether, as was previously thought, said Dr. Tagir Abdylmyanov, Associate Professor from Kazan State Power Engineering University in Russia. Abdylmyanovs research, which models the movements of particles in fluids and gasses and in the gas cloud from which our Sun accreted, indicates that the first series of shockwaves during short but very rapid changes in solar activity would have created the proto-planetary rings for Uranus, Neptune, and dwarf planet Pluto first. Jupiter, Saturn, and the asteroid belt would have come next during a series of less powerful shockwaves. Mercury, Venus, Earth, and Mars would have formed last, when the Sun was far calmer. This means that our own planet is one of the youngest in the Solar System. It is difficult to say exactly how much time would have separated these groups, Abdylmyanov said, but the proto-planetary rings for Uranus, Neptune and Pluto would have likely formed very close to the Suns birth. 3 million years later and we would see the debris ring destined to form Saturn. Half a million years after this we would see something similar but for Jupiter. The asteroid belt would have begun to form about a million years after that, and
Researchers Present the Sharpest Image of Pluto Ever Taken from Earth After taking a series of quick snapshots of Pluto and Charon using a recently-developed camera called the Differential Speckle Survey Instrument (DSSI), which was mounted on the Gemini Observatorys 8-meter telescope in Hawaii, researchers combined them into a single image while canceling out the noise caused by turbulence and optical aberrations. This speckle imaging technique resulted in an incredibly clear, crisp image of the distant pair of worlds - especially considering that 1. it was made with images taken from the ground, 2. Pluto is small, and 3. Pluto is very, very far away. Less than 3/4 the diameter of our Moon, Pluto (and Charon, which is about half that size) are currently circling each other about 3 billion miles from Earth - 32.245 AU to be exact. Thats a long way off, and theres still much more that we dont know than we do about the dwarf planets system. New Horizons will fill in a lot of the blanks when it passes close by Pluto in July 2015, and images like this can be a big help to mission scientists who want to make sure the spacecraft is on a safe path. In addition, the high resolution achievable through the teams speckle imaging technique may also be used to confirm the presence of exoplanet candidates discovered by Kepler. With an estimated 3- to 4-magnitude increase in imaging sensitivity, astronomers may be able to use it to pick out the optical light reflected by a distant Earth-like world around another star. Speckle imaging has been used previously to identify binary star systems, and with the comparative ability to separate a pair of automobile headlights in Providence, RI, from San Francisco, CA theres a good chance that it can help separate an exoplanet from the glare of its star as well.
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A The first speckle reconstructed image for Pluto and Charon from which astronomers obtained not only the separation and position angle for Charon, but also the diameters of the two bodies. North is up, east is to the left, and the image section shown is 1.39 arcseconds across. Resolution of the image is about 20 milliarcseconds rms. Credit: Gemini Observatory/NSF/NASA/AURA
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Hubble: Stunning New Deepest View Ever of the Universe Oh my! The Hubble Space Telescope has just outdone itself, taking the deepest-ever view of the Universe. But the new image really is a compilation of work over the past ten years, as the eXtreme Deep Field, or XDF was assembled by combining ten years of observations, with over 2 million seconds of exposure time, taken of a patch of sky in the center of the original Hubble Ultra Deep Field from 2004. The XDF is a small fraction of the angular diameter of the full Moon. The new full-color XDF image is even more sensitive than the Hubble Ultra Deep Field image from 2004 and the original Hubble Deep Field image from 1995. The new XDF image contains about 5,500 galaxies, even within its smaller field of view. The faintest galaxies are one ten-billionth the brightness that the unaided human eye can see. The XDF is the deepest image of the sky ever obtained and reveals the faintest and most distant galaxies ever seen. XDF allows us to explore further back in time than ever before, said Garth Illingworth of the University of California at Santa Cruz, principal investigator of the Hubble Ultra Deep Field 2009 (HUDF09) program. Just take a look: magnificent spiral galaxies similar in shape to the Milky Way and Andromeda galaxies, as well as large, fuzzy red and dead galaxies that are no longer producing stars. Peppered across the field are tiny, faint, and yet more distant galaxies that are like the seedlings from which todays magnificent galaxies grew. The history of galaxies - from soon after the first galaxies were born to the great galaxies of today, like the Milky Way - is laid out in this one remarkable image. Hubble was pointed at a tiny patch of southern sky in repeat visits made over the past decade with more than 2,000 images of the same field taken with Hubbles two primary cameras: the Advanced Camera for Surveys and the Wide Field Camera 3, which extends Hubbles vision into near-infrared light. These were then combined to form the XDF. The Universe is 13.7 billion years old, and incredibly, the XDF reveals galaxies that span back 13.2 billion years in time. Most of the galaxies in the XDF are seen when they were young, small, and growing, often violently as they collided and merged together. Astronomers are already planning to outdo this image. They are planning to aim the James Webb Space Telescope (at the XDF, and will study it with its infrared vision. The Webb telescope will find even fainter galaxies that existed when the Universe was just a few hundred million years old. Because of the expansion of the Universe, light from the distant past is stretched into longer, infrared wavelengths. The Webb telescopes infrared vision is ideally suited to push the XDF even deeper, into a time when the first stars and galaxies formed and filled the early dark ages of the Universe with light.
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Distances in the Hubble eXtreme Deep Field. Credit: Hubble
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The Hubble eXtreme Deep Field (XDF) combines Hubble observations taken over the past decade of a small patch of sky in the constellation of Fornax. With a total of over two million seconds of exposure time, it is the deepest image of the Universe ever made. Credit:: NASA, ESA, G. Illingworth, D. Magee, and P. Oesch (University of California, Santa Cruz), R. Bouwens (Leiden University), and the HUDF09 Team
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Hubble: Fireworks Erupt From Newborn Star Herbig-Haro (HH) objects come in a wide array of shapes, but the basic configuration stays the same. Twin jets of heated gas, ejected in opposite directions away from a forming star, stream through interstellar space. Astronomers suspect that these outflows are fueled by gas accreting onto a young star surrounded by a disk of dust and gas. The disk is the fuel tank, the star is the gravitational engine, and the jets are the exhaust. When these energetic jets slam into colder gas, the collision plays out like a traffic jam on the interstate. Gas within the shock front slows to a crawl, but more gas continues to pile up as the jet keeps slamming into the shock from behind. Temperatures climb sharply, and this curving, flared region starts to glow. These bow shocks are so named because they resemble the waves that form at the front of a boat. In the case of the single HH 110 jet, astronomers observe a spectacular and unusual permutation on this basic model. Careful study has repeatedly failed to find the source star driving HH 110, and there may be good reason for this: perhaps the HH 110 outflow is itself generated by another jet. Astronomers now believe that the nearby HH 270 jet grazes an immovable obstacle - a much denser, colder cloud core - and gets diverted off at about a 60-degree angle. The jet goes dark and then reemerges, having reinvented itself as HH 110. The jet shows that these energetic flows are like the erratic outbursts from a Roman candle. As fast-moving blobs of gas catch up and collide with slower blobs, new shocks arise along the jets interior. The light emitted from excited gas in these hot blue ridges marks the boundaries of these interior collisions. By measuring the current velocity and positions of different blobs and hot ridges along the chain within the jet, astronomers can effectively rewind the outflow, extrapolating the blobs back to the moment when they were emitted. This technique can be used to gain insight into the source stars history of mass accretion. This image is a composite of data taken with Hubbles Advanced Camera for Surveys in 2004 and 2005 and the Wide Field Camera 3 in April 2011. (Source: Universe Today/Nancy Atkinson)
News ATM Update
Just in time for summer fireworks season, the Hubble science team has released an image of Herbig-Haro 110, a young star with geysers of hot gas skyrocketing away through interstellar space. Twin jets of heated gas are being ejected in opposite directions from this star that is still in the formation process. The Hubble team says these outflows are fueled by gas falling onto the young star, which is surrounded by a disc of dust and gas. If the disc is the fuel tank, the star is the gravitational engine, and the jets are the exhaust. And even though the plumes of gas look like whiffs of smoke, they are actually billions of times less dense than the smoke from a fireworks display. Credit: Hubble
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LRO: Barnstorming the Moons Giordano Bruno Crater At the 2012 Lunar Science Forum going on this week at the NASA Lunar Science Institute, scientist Mark Robinson presented some new stunning images from the Lunar Reconnaissance Orbiters cameras (LROC), including this oblique view Giordano Bruno crater, and a wonderful video (below) that allows viewers to barnstorm over the crater to witness the stark beauty of this impact basin. I could spend weeks and months looking at the preserved materials in the crater, Robinson said, adding that views like this are helping scientists to understand the impact process. Until astronauts visit Giordano Bruno, this gives a view about as close as you can get to standing on the surface to the west of the crater. Robinson is the Principal Investigator for LROC, and in his talk today said all systems on LROC are working nominally. Thats NASA-speak for everything is fantastic, he joked. With the wide angle camera, LROC has mapped the entire Moon nearly 33 times. Every map has a different photometric geometry, so this is not a redundant dataset, Robinson said, adding that the different lighting provides different ways to study the Moon. And to be able to do follow-up observations, I cant tell you how great it is.
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Southern rim of Giordano Bruno crater seen obliquely by LROC. Credit: NASA/GSFC/Arizona State University
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Just about every month, the science team is able to take new mosaics of both the north and south pole, and theyve also found 160 pits - lunar caves - so far. These caves with skylights are intriguing because they would offer potential protective habitats for future lunar explorers. Now in its extended mission, LRO is still going strong, and has provided incredible details of the lunar surface. LRO project scientist Richard Vondrak said since the start of the mission, LRO has uploaded 325 terabytes of data into the Planetary Data System, the digital storehouse for NASA science mission, through June 2012. Thanks to LRO, the Moons topography is now better understood than the Earth, since two-thirds of Earth is covered by water, Vondrak said. But both scientists agrees LRO is just getting started. The Moon is one of the most engaging bodies in the Solar System and weve still got a lot of work to do, Robinson said Robinson suggests scrolling through all of the details of this beautiful impact crater by looking at the fullresolution version of Giordano Crater not to be missed! he said. Caption: Southern rim of Giordano Bruno crater seen obliquely by LROC. Credit: NASA/GSFC/Arizona State University At the 2012 Lunar Science Forum going on this week at the NASA Lunar Science Institute, scientist Mark Robinson presented some new stunning images from the Lunar Reconnaissance Orbiters cameras (LROC), including this oblique view Giordano Bruno crater, and a wonderful video (below) that allows viewers to barnstorm over the crater to witness the stark beauty of this impact basin. I could spend weeks and months looking at the preserved materials in the crater, Robinson said, adding that views like this are helping scientists to understand the impact process. Until astronauts visit Giordano Bruno, this gives a view about as close as you can get to standing on the surface to the west of the crater. Robinson is the Principal Investigator for LROC, and in his talk today said all systems on LROC are working nominally. Thats NASA-speak for everything is fantastic, he joked. With the wide angle camera, LROC has mapped the entire Moon nearly 33 times. Every map has a different photometric geometry, so this is not a redundant dataset, Robinson said, adding that the different lighting provides different ways to study the Moon. And to be able to do follow-up observations, I cant tell you how great it is. Just about every month, the science team is able to take new mosaics of both the north and south pole, and theyve also found 160 pits - lunar caves - so far. These caves with skylights are intriguing because they would offer potential protective habitats for future lunar explorers. Now in its extended mission, LRO is still going strong, and has provided incredible details of the lunar surface. LRO project scientist Richard Vondrak said since the start of the mission, LRO has uploaded 325 terabytes of data into the Planetary Data System, the digital storehouse for NASA science mission, through June 2012. Thanks to LRO, the Moons topography is now better understood than the Earth, since two-thirds of Earth is covered by water, Vondrak said. But both scientists agrees LRO is just getting started. The Moon is one of the most engaging bodies in the Solar System and weve still got a lot of work to do, Robinson said Robinson suggests scrolling through all of the details of this beautiful impact crater by looking at the fullresolution version of Giordano Crater not to be missed! he said. (Source: Universe Today/Nancy Atkinson)
News ATM Update

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Close-up detail of the rim of Giordano Crater. Credit: NASA/GSFC/Arizona State University
News ATM Update

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Hubble: The Last Outbursts of a Dying Star As stars approach the inevitable ends of their lives they run out of stellar fuel and begin to lose a gravitational grip on their outermost layers, which can get periodically blown far out into space in enormous gouts of gas - sometimes irregularly-shaped, sometimes in a neat sphere. The latter is the case with the star above, a red giant called U Cam in the constellation Camelopardalis imaged by the Hubble Space Telescope. U Cam is an example of a carbon star. This is a rare type of star whose atmosphere contains more carbon than oxygen. Due to its low surface gravity, typically as much as half of the total mass of a carbon star may be lost by way of powerful stellar winds. Located in the constellation of Camelopardalis (The Giraffe), near the North Celestial Pole, U Cam itself is actually much smaller than it appears in Hubbles picture. In fact, the star would easily fit within a single pixel at the center of the image. Its brightness, however, is enough to saturate the cameras receptors, making the star look much bigger than it really is. The shell of gas, which is both much larger and much fainter than its parent star, is visible in intricate detail in Hubbles portrait. While phenomena that occur at the ends of stars lives are often quite irregular and unstable, the shell of gas expelled from U Cam is almost perfectly spherical. (Source: UT/Jason Major)
News ATM Update
Credit: Hubble
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Hubble: Tiny, Ancient Ghost Galaxies Theyre out there; tiny, extremely faint and incredibly ancient dwarf galaxies with so few stars that scientists call them ghost galaxies. NASAs Hubble Space Telescope captured images of three of these small-fry galaxies in hopes of unravelling a mystery 13 billion years in the making. Astronomers believe these tiny, ghost-like galaxies spotted alongside the Milky Way Galaxy are among the oldest, tiniest and most pristine galaxies in the Universe. Hubble views reveal that their stars share the same birth date. The galaxies all started forming stars more than 13 billions years ago but then abruptly stopped within just one billion years after the Universe was born. These galaxies are all ancient and theyre all the same age, so you know something came down like a guillotine and turned off the star formation at the same time in these galaxies, said Tom Brown of the Space Telescope Science Institute in Baltimore, Md., the studys leader. The most likely explanation is reionization. Reionization of the Universe began in the first billion years after the Big Bang. During this time, radiation from the first stars knocked electrons off hydrogen atoms, ionizing the hydrogen gas. This process also allowed hydrogen gas to become transparent to ultraviolet light. This same process may also have squashed star-making in dwarf galaxies, such as those in Browns study. These galaxies are tiny cousins to star-making dwarf galaxies near the Milky Way. And because of their small size, just 2,000 light-years across, they were not massive enough to shield themselves from the harsh ultraviolet light of the early Universe which stripped away their meager supply of hydrogen gas, leaving them unable to make new stars. Astronomers proposed many reasons for the lack of stars in these galaxies in addition to the reioniation theory. Some scientists believed internal events such as supernovae blasted away the gas needed to create new stars. Others suggested that the galaxies simply used up their supply of hydrogen gas needed to make stars.
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These Hubble images show the dim, star-starved dwarf galaxy Leo IV. The image at left shows part of the galaxy, outlined by the white rectangular box. The box measures 83 light-years wide by 163 light-years long. The few stars in Leo IV are lost amid neighboring stars and distant galaxies. A close-up view of the background galaxies within the box is shown in the middle image. The image at right shows only the stars in Leo IV. The galaxy, which contains several thousand stars, is composed of sun-like stars, fainter, red dwarf stars, and some red giant stars brighter than the sun. Credit: NASA, ESA, and T. Brown (STScI)
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Brown measured the stars ages by looking at their brightness and colors. The stellar populations in these fossil galaxies range from a few hundred to a few thousand stars; some sun-like, some red dwarfs and some red stars larger than our Sun. When evidence showed that the stars were indeed ancient, Brown enlisted the help of Hubbles Advanced Camera for Surveys to burrow deep within six galaxies to determine when they were born. So far, the team has finished analyzing data for three; Hercules, Leo IV and Ursa Major. The galaxies lie between 330,000 light-years to 490,000 light-years. For comparison, Brown compared the galaxies stars with those found in M92, a 13 billion-year-old globular cluster located about 26,000 light-years from Earth. He found they are of similar age. These are the fossils of the earliest galaxies in the universe, Brown said. They havent changed in billions of years. These galaxies are unlike most nearby galaxies, which have long star-formation histories. Browns discovery could help explain the so-called missing satellite problem. Astronomers have observed only a few dozen dwarf galaxies around the Milky Way while computer simulations predict thousands should exist. But perhaps they do exist. The Sloan survey found more than a dozen tiny, star-starved galaxies in the Milky Ways neighborhood while scanning just a portion of the sky. Astronomers think that dozens more ultra-faint galaxies may lurk undetected with the possibility of thousands of even smaller dwarfs containing virtually no stars. The tiny galaxies may be star-deprived but they still have an abundance of dark matter, the framework upon which galaxies are built. Normal dwarf galaxies near the Milky Way Galaxy contain ten times more dark matter than ordinary visible matter. Brown explains that these tiny galaxies are now islands of mostly dark matter, unseen for billions of years until astronomers began finding them in the Sloan Survey.
News ATM Update
These computer simulations show a swarm of dark matter clumps around our Milky Way galaxy. Some of the dark-matter concentrations are massive enough to spark star formation. Thousands of clumps of dark matter coexist with our Milky Way galaxy, shown in the center of the top panel. The green blobs in the middle panel are those dark-matter chunks massive enough to obtain gas from the intergalactic medium and trigger ongoing star formation, eventually creating dwarf galaxies. In the bottom panel, the red blobs are ultra-faint dwarf galaxies that stopped forming stars long ago. Credit: NASA, ESA, and T. Brown and J. Tumlinson (STScI)
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Hubble: Fifth Moon Found Around Pluto This just in! Astronomers working with the Hubble Space Telescope have spotted a new moon around distant Pluto, bringing the known count up to 5. The image above was released by NASA just minutes ago, showing the Pluto system with its newest member, P5. This news comes just a couple of weeks shy of the one-year anniversary of the announcement of Plutos 4th known moon, still currently named P4.The news was shared this morning by an undoubtedly excited Alan Stern of the Southwest Research Institute (SwRI) on Twitter. Astronomers estimate P5 to be between 6 and 15 miles (9.6 to 24 km) in diameter. It orbits Pluto in the same plane as the other moons - Charon, Nix, Hydra and P4. The moons form a series of neatly nested orbits, a bit like Russian dolls, said team lead Mark Showalter of the SETI Institute. A mini-abstract of an upcoming paper lists image sets acquired on 5 separate occasions in June and July. According to the abstract, P5 is 4% as bright as Nix and 50% as bright as P4. The new detection will help scientists navigate NASAs New Horizons spacecraft through the Pluto system in 2015, when it makes an historic and long-awaited high-speed flyby of the distant world.
News ATM Update
The satellites mean magnitude is V = 27.0 +/- 0.3, making it 4 percent as bright as Pluto II (Nix) and half as bright as S/2011 (134340) 1. The diameter depends on the assumed geometric albedo: 10 km if p_v = 0.35, or 25 km if p_v =0.04. The motion is consistent with a body traveling on a near-circular orbit coplanar with the other satellites. The inferred mean motion is 17.8 +/- 0.1 degrees per day (P = 20.2 +/- 0.1 days), and the projected radial distance from Pluto is 42000 +/- 2000 km, placing P5 interior to Pluto II (Nix) and close to the 1:3 mean motion resonance with Pluto I (Charon). Credit: Hubble
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Books Review
Catchers of the Light A History of Astrophotography by Stefan Hughes Recent Interferometry Applications in Topography and Astronomy, by Ivan Padron, Publisher: InTeO, 2012, 229 pages, ISBN: 9535104049
Available from: www.catchersofthelight.com
Available from: amazon.com
Every day our eyes catch the light of our memories - time spent with family, the journey to work, a special holiday, a beautiful sunset or a dark starlit night. Each image captured is a picture drawn in light - a photograph: only to be lost in our minds or forever forgotten. Nearly two hundred years ago a small group of amateur scientists achieved what had eluded mankind for centuries - the ability to capture a permanent record of an image seen by their own eyes - a moment in time frozen onto a surface. They had discovered Photography. They were the Catchers of the Light. Catchers of the Light is the first comprehensive and fully researched History of Astrophotography. It begins with the work of the early pioneers of photography; then tells the story of the first astronomical photographs of the Moon and Sun; of the race between nations to be the first to capture a total solar eclipse; and the problems encountered by astronomers when attempting to image the Planets and other bodies of our Solar System.
This book provides a current overview of the theoretical and experimental aspects of some interferometry techniques applied to Topography and Astronomy. Each chapter offers an opportunity to expand the knowledge about interferometry techniques and encourage researchers in development of new interferometry applications. The first two chapters comprise interferometry techniques used for precise measurement of surface topography in engineering applications; while chapters three through eight are dedicated to interferometry applications related to Earth's topography. The last chapter is an application of interferometry in Astronomy, directed specifically todetection of planets outside our solar system.
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Books Review
The Early Years of Radio Astronomy by W. T. Sullivan, Publisher: Cambridge University Press, 1984, 416 Pages, ISBN: 052125485X Radio astronomy has revolutionized the course of modern astronomy. Marking the fiftieth anniversary of Jansky's discovery in 1933 of extraterrestrial radio emission, Professor Sullivan asked many of the pioneers in the field to set down their versions of events and the people who made them. Each of the score of contributors seeks to give a good 'feeling' for the times to the great majority of readers who will not have experienced them. Over 150 illustrations, mostly historical photographs of men and machines, enliven the various recollections and reflections. The list of contributors includes many of the key personalities and covers all the major laboratories and countries involved in radio astronomy before 1960. In addition to the radio astronomers themselves, there are contributions from optical astronomers and theorists closely related to the field, as well as historians of twentieth century astronomy.
Astronomy: Understanding the Universe by Sherman Hollar, Publisher: Rosen Education Service, 2011, 96 pages, ISBN: 1615305203 Fathoming the boundlessness of space and the universe, we are immediately filled with curiosity about our own origins and wonder about the objects, life forms, and matter that populate the cosmos. Through the observations and work of astronomers over time, we have slowly been able to reduce the number of unknowns and develop explanations or theories for some of the celestial objects and phenomena we see. This spacetraveling survey recounts some of the major discovery milestones in the field of astronomy and examines the tools and techniques currntly used by astronomers to study the universe.
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Books Review
works, Martens explores the complex interplay between changes in his philosophical views and the status of his astronomical discoveries. She shows how Kepler's philosophy paved the way for the discovery of elliptical orbits and provided a defense of physical astronomy's methodological soundness. In doing so, Martens demonstrates how an empirical discipline was inspired and profoundly shaped by philosophical assumptions. From Eudoxus to Einstein: A History of Mathematical Astronomy by C. M. Linton, Publisher: Cambridge University Press, 2004, 529 pages, ISBN: 0521827507 Since humans first looked towards the heavens, they have attempted to predict and explain the motions of the sun, moon, and planets. This book describes the theories of planetary motion that have been developed through the ages, from the homocentric spheres of Eudoxus to Einstein's general theory of relativity. It emphasizes the interaction between progress in astronomy and in mathematics, demonstrating how the two have been inextricably linked since Babylonian times. This valuable text is accessible to a wide audience, from amateur astronomers to professional historians of astronomy.
Kepler's Philosophy and the New Astronomy by Rhonda Martens, Princeton University Press, 2000, 216 pages, ISBN: 0691050694 Johannes Kepler contributed importantly to every field he addressed. He changed the face of astronomy by abandoning principles that had been in place for two millennia, made important discoveries in optics and mathematics, and was an uncommonly good philosopher. Generally, however, Kepler's philosophical ideas have been dismissed as irrelevant and even detrimental to his legacy of scientific accomplishment. Here, Rhonda Martens offers the first extended study of Kepler's philosophical views and shows how those views helped him construct and justify the new astronomy. Martens notes that since Kepler became a Copernican before any empirical evidence supported Copernicus over the entrenched Ptolemaic system, his initial reasons for preferring Copernicanism were not telescope observations but rather methodological and metaphysical commitments. Further, she shows that Kepler's metaphysics supported the strikingly modern view of astronomical method that led him to discover the three laws of planetary motion and to wed physics and astronomy a key development in the scientific revolution. By tracing the evolution of Kepler's thought in his astronomical, metaphysical, and epistemological
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Books Review
discussion of the role of partial coherence in image formation and factors that affect image quality, as well as the role of optical metrology and wavefront sensing and control in astronomical telescopes presentation of the fundamentals of optics, such as image location and size, geometrical image quality, image brightness, scalar diffraction and image formation, interference of light, and radiometry investigations of segmented telescopes and their applications and performance metrics, sparse-aperture telescopes, and the optical challenges of designing and building telescopes or instruments for detecting and characterizing exoplanets
Basic Optics for the Astronomical Sciences by James B. Breckinridge, SPIE Press Book, ISBN: 9780819483669, 448 pages This text was written to provide students of astronomy and engineers an understanding of optical science the study of the generation, propagation, control, and measurement of optical radiation as it applies to telescopes and instruments for astronomical research in the areas of astrophysics, astrometry, exoplanet characterization, and planetary science. The book provides an overview of the elements of optical design and physical optics within the framework of the needs of the astronomical community. Features of this text include: an historical perspective on the development of telescopes and their impact on our understanding of the universe a review of the optical measurements that astronomers record, and identification of the attributes for ground and space observations presentation of the fundamentals of optics, such as image location and size, geometrical image quality, image brightness, scalar diffraction and image formation, interference of light, and radiometry
PREFACE Astronomical science advances use the following research cycle: measure parts of the universe, develop theories to explain the observations, use these new theories to forecast or predict observations, build new telescopes and instruments, measure again, refine the theories if needed, and repeat the process. Critical to the success of this cycle are new observations, which often require new, more sensitive, efficient astronomical telescopes and instruments. Currently, the field of astronomy is undergoing a revolution. Several new important optical/infrared windows into the universe are opening as a result of advances in optics technology, including systems using high angular resolution, very high dynamic range, and highly precise velocity and position measurements. High-angular-resolution systems, which incorporate adaptive optics and interferometry, promise gains of more than 104 in angular resolution on the sky above our current capabilities. Advanced coronagraphs enable very high-dynamic-range systems that enable astronomers to image an exoplanet in the presence of the blinding glare from its parent star that is more than 1012 times brighter. Optical science is the study of the generation, propagation, control, and measurement of optical radiation. The optical region of the spectrum is considered to range across the wavelength region of ~0.3 to ~50 m, or from the UV through the visual and into the far infrared. Different sensors or detectors are used for covering sections of this broad spectral region. However, the analysis tools required to design, build, align, test, and characterize these optical systems are common: geometrical raytracing, wavefront abe-
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Books Review
rration theory, diffraction theory, polarization, partial coherence theory, radiometry, and digital image restoration. Advances in allied disciplines such as material science, thermal engineering, structures, dynamics, control theory, and modeling within the framework of the tolerances imposed by optics are essential for the next generation of telescopes. This text provides the background in optics to give the reader insight into the way in which these new optical systems are designed, engineered, and built. The book is intended for astronomy and engineering students who want a basic understanding of optical system engineering as it is applied to telescopes and instruments for astronomical research in the areas of astrophysics, astrometry, exoplanet characterization, and planetary science. Giant ground-based optical telescopes such as the Giant Segmented Mirror Telescope, the Thirty Meter Telescope, and the Extremely Large Telescope are currently under development. The James Webb Space Telescope is under construction, and the Space Interferometer Mission has successfully completed its technology program. The astronomical sciences are, indeed, at the threshold of many new discoveries. Chapter 1 provides an historical perspective on the development of telescopes and their impact on our understanding of the universe. Chapter 2 reviews the optical measurements astronomers record and identifies the attributes for ground and space observatories. Chapter 3 provides the tools used for obtaining image location, size, and orientation and presents the geometrical constraints that need to be followed to maximize the amount of radiation passed by the system. Chapter 4 presents geometrical aberration theory and introduces the subject of image quality. Chapter 5 provides methods to maximize the amount of radiation passing through the optical system: transmittance, throughput, scattered light, and vignetting. Chapter 6 provides a basic introduction to radiative transfer through an optical system and identifies several factors needed to maximize the signal-to-noise ratio. Chapter 7 provides an introduction to the optics of the atmosphere necessary for ground-based astronomers. Chapter 8 introduces the scalar and vector wave theories of light and identifies sources of instrumental polarization that will affect the quality of astronomical data. Using the Fourier transform, Chapter 9 provides an in-depth analysis of the propagation of scalar waves through an optical system as the basis of a discussion on the effects of astronomical telescopes and instruments on image quality. Chapter 10 provides a discussion of interferometry within the framework of partial coherence theory. The Fourier transform spectrometer, the Michelson stellar interferometer, and the rotational shear interferometer are used as examples and are analyzed in detail. Chapter 11, coauthored with Siddarayappa Bikkannavar, discusses the important new role that optical metrology and wavefront sensing and control play in the design and construction of very large ground- and space-based telescopes. These 11 chapters have formed the basis of the Optical System Engineering class given by the author at CALTECH. Chapter 12 provides an analysis that is fundamental to the understanding of segmented-aperture telescopes and how they enable the next-generation, very large groundand space-based telescopes. Chapter 13 presents an analysis of sparse-aperture telescopes, describes how they are used for extremely high angular resolution, and identifies their limitations. Chapter 14 discusses astrometric and imaging interferometry within the framework of basic optics. Chapter 15 develops basic concepts for extreme-contrast systems such as coronagraphs for the characterization of exoplanet systems. James B. Breckinridge Pasadena, California April 2012
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Review - Powerseeker 80EQ Refractor Telescope
Did you ever have a T-shirt that you really enjoyed and wore until you wore it out? How about
Review
a favorite pair of slippers? You know, the ones with the duct tape soles? Then I think youre going to feel the same way about this telescope. Its darn near the perfect combination of power, portability and price. Just right for casual observing Be it on a rooftop or from your suburban yard. What makes it even more attractive is its ability to track its subject matter! Whats new on the Tammy-testing homefront? This time its an Optics Planet Celestron PowerSeeker 80EQ refractor telescope. With 80mm of aperture and a 900mm focal length, it is not a small tube. It is elegant in both lines and size and does not appear spindly. Unlike most small aperture refractors which favor the alt/az, it comes with a light weight equatorial mount with a delightful addition - a drive unit. This means this special edition PowerSeeker 80EQ is going to make your time with lunar and planetary studies much more pleasant, and make higher magnification much more user-friendly. Assembly is quite easy and fairly intuitive if you are familiar with telescopes and equatorial mounts. One thing you will very much enjoy is how easy it is to handle - a manageable 19 lbs. (8.62 kg) total weight. This means it is light enough to be set up complete and ready to be set outside the door at a moments notice. (This is something that I very much enjoy and approve of in a telescope. While I find large aperture to be breathtaking and I demand it for serious study, I also want a telescope thats on hand for a quick look at the Moon or a joyous half hour with a planet.) While a light weight mount is super, dont forget youre making a trade-off. Its not going to support heavy camera equipment and its not going to take a lot of abuse, such as overtightening or stressing gears through imbalance. However, it is quite capable of adding on certain types of imaging equipment, such as a webcam or eyepiece camera, or piggybacking a smaller camera on the mounting rings. Next up? The view. As always, Celestron comes through with quality optics. At 80mm youre not going to be getting Hubble images, but bright objects are crisp and clean. The views of Saturn and Mars were quite satisfactory and thanks to the included drive unit, the Celestron Powerseeker 80EQ delivered a whisper of the Cassini division and the neat little apparition of Titan swinging around the outside. Even Mars was capable of showing some dark patches when the atmosphere held still! Unfortunately, there wasnt any Moon at the time, but I was very pleased with the color correction on beautiful double stars such as Cor
Caroli and Albireo. Even Collinder 399 the Coat Hanger showed pleasing red hints! Again, I was very appreciative of the drive unit when trying to split Epsilon Lyrae. With smaller aperture, the f/11 focal ratio could handle it - but again, needed the moment of perfect steadiness to say it was a clean split. No offense, but both the included 3X barlow and 4mm eyepiece are simply too much magnification for this scope to handle. (But a nice 10mm Plossl sure fills the bill!) As for the scope itself, youll find it feels very healthy. The focuser isnt a Feathertouch, but it has a nice feel to it positive and it doesnt slop around with a heavier eyepiece in it. The included 524 finderscope might seem a little small to most observers, but I liked it for two reasons - its an optical finderscope and its appropriately sized to what the scope can achieve. Its just enough to pick off fainter star hop marker stars and give a hint of brighter objects. The included 1.25 diagonal is also quite satisfactory and the 20mm eyepiece is the perfect workhorse for the majority of observations. You would be impressed with the crisp quality of the views of the Double Cluster, the ethereal Wild Ducks and the slightly pincushion look of M2. Next up? Try kicking in better eyepieces and youll surprise yourself. Without getting brand specific, a higher dollar Plossl and a high magnification ED. Surprise, surprise! Here again, Celestron telescopes show their optical quality as the view did improve. After having become so accustomed to fast telescopes, it was a real pleasure to work with a longer focal ratio and see just how far I could push it. The Celestron Powerseeker 80 is definately deserving of higher quality eyepieces and a diagonal. All in all, this is an inexpensive telescope that is well made and, with care, should last through years of observing. You some day may end up with a little duct tape here and there But its got soul. My thanks go to Optics Planet for their generous donation of the Celestron Powerseeker 80EQ to our annual star party/fundraiser at Warren Rupp Observatory. (Source: Universe Today/Tammy Plotner)
PowerSeeker 80 has surprisingly good optics as you can see from this close up view of a fault line known as the straight wall.
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Powerseeker 80EQ Refractor Telescope
Powerseeker 80EQ Refractor Telescope
Review
The planet Jupiter, image captured with PowerSeeker 80 telescope, Celestron NexImage and 2x barlow.
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Rambling Through The Years
Andrew Ainslie Common: The Common Man by Stefan Hughes
Andrew Ainslie Common was without doubt one of the great pioneers of Astrophotography. His chief claim to fame lies, not particularly because of the photographs he took, but in the techniques and procedures he used to capture them, and even more importantly in the telescopes he constructed and designed specifically for Deep Space Astrophotography
Andrew Ainslie Common (1841 - 1903)
Andrew Ainslie Common was a pioneer in the construction of large silvered mirror telescopes. He showed the potential of such instruments to photograph the heavens provided they were accurately driven. Two of his telescopes are still in operation today. He was one of the great Astrophotographers Procedures & Techniques Andrew Ainslie Common was without doubt one of the great pioneers of Astrophotography, not particularly because of the photographs he took; in fact he took very few during the course of his lifetime. His chief claim to fame lies in the techniques and procedures he used to capture them, but even more importantly in the telescopes he constructed and designed specifically for Deep Sky Astrophotography. His legacy lives on today, for two of the great reflecting telescopes he constructed over a century ago, are still in use and helping us understand the universe in which Andrew Common first gazed upon so long ago. Let us now turn the pages of history back over 150 years to a world far different from the one fate decreed Andrew Ainslie Common would follow. Newcastle-upon-Tyne Andrew Ainslie Common was born on the 7th August 1841 in Oxford Street, in the parish of St. Andrews, Newcastle-upon-Tyne, the second of the three children of Thomas Common, a surgeon of that city, and his wife Mary (nee Hall). The area of Newcastle where Andrew Common was born was at the time a new residential area on the outskirts of the city. The empty spaces around
Bibliography
his home were soon to disappear as the citys population rapidly expanded in the coming years; as is evident from the map which shows the ominous presence of land allocated for new buildings in 1843. It maybe thought that Andrew was immune from the poverty, disease and depravation that many tens of thousands in the city were accustomed to. This was far from being the case, indeed the opposite was true. His father, Thomas Common was a respected and well known surgeon in the North of England, being one of the early pioneers in the field of eye cataract surgery. He had qualified as a Surgeon and Apothecary, becoming a member of the Royal College of Surgeons in 1832, aged 22. He subsequently trained other Apprentice Surgeons, who later would make great contributions to helping the poor, sick and needy in the city; the most well known being Dr. Charles John Gibb, the
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Andrew Ainslie Common - The Common Man
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Born: 7th of August 1841, Newcastle-upon-Tyne, Northumberland, England. Died: 2nd of June 1903, Ealing, Middlesex, England. Andrew Ainslie Common was without doubt one of the great pioneers of Astrophotography. His chief claim to fame lies, not particularly because of the photographs he took, but in the techniques and procedures he used to capture them, and even more importantly in the telescopes he constructed and designed specifically for Deep Space Astrophotography. Two of his telescopes are still in operation today, the 36-inch Crossley reflector at the Lick Observatory in California and the 60inch Rockefeller reflector at the Boyden Observatory, Bloemfontein, South Africa. He believed that the telescopes of the future should be silvered mirrored reflectors and not the Great Refractors which at that time, were to be found under the domes all the Great Observatories of the world. Furthermore, if they were to be of any use to astronomers, they should be on a stable platform of such, a construction of mounting as to give the greatest mount of steadiness with the least amount of motion; provided with a Driving clock. Circles to find or identify an object and motions taken to eye end and most important of all a suitable locality for the erection of the telescope. Added by the Editor
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House Surgeon at the Newcastle Infirmary. As a young boy growing up in Newcastle with his brother John and his sister Mary, he was always aware of the fragility of life. His fathers profession must have been a constant reminder to him of this hard lesson. The city of Newcastle had during the period 1831 to 1853 suffered a number of cholera epidemics caused by poor sanitation and the presence of much slum housing. In 1842, the year following Andrews birth his father was appointed the resident surgeon at the nearby Gateshead Dispensary. The Gateshead Dispensary was established in 1832 as a direct consequence of the cholera the previous year. Its purpose was to provide free medical care to those unable to pay for it - the poor and the deprived. As is always the way it was too little too late - the cholera outbreak of 1831 had already killed 306 people. It had taken this shock treatment for the great and the good of Gateshead to be stirred into action! Morpeth Thomas and Mary Common tried as best they could to shield their young children from the lives of those less fortunate from themselves and perhaps to avoid bringing sickness on them. As a result of this concern the family moved from the city of Newcastle itself and Thomas Commons work, to the more pleasant surrounding of the market town of Morpeth. By the time of the 1851 Census the family are to be found living at No. 16 Newgate Street, although Thomas Common was not at home, but visiting a fellow surgeon Mr. Frederick Beavan at his home in Shotley. Andrew Common was about ten years old when he first became interested in Astronomy; and often used a telescope his mother had borrowed from a young surgeon called John Pickering Bates; whose parents John and Isabella Bates owned the grocers shop at No. 94 Newgate Street, just up the road from where they lived. However, Andrew Commons newly found passion for Astronomy was abruptly and tragically put on hold. In about 1852 Thomas Common died, leaving his family in poor financial circumstances, but not destitute. It is known that Mary Common was in receipt of annuities as is evident from the 1851 Census which lists her as married with the added status of Annuitant. Furthermore, Mary Common had two other things going for her - firstly, the help and support she received from her three brothers Matthew, George and Walter Hall; and secondly the sheer determination and resourcefulness of her own children. The Hall family into which Mary was born was a large one. Her f ather Walter Hall and her mother
All Saints Church, Newcastle, Andrew Common was baptised here 2nd September 1841.
Charles Gibb Indenture 1st July 1841 Apprentice to Thomas Common, Surgeon.
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Jane (nee Anderson) had six daughters including Mary and three brothers. It was also a knit close family who also possessed tremendous business sense. In 1841, Marys two brothers George and Walter lived with Thomas and Mary Common at Oxford Street, Newcastle; whilst her other brother Matthew Hall was fully occupied with his business activities - something which he never stopped doing.
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Top: Gateshead Dispensary, Nelson Street, (1832 1946) Plaque. Bottom: Gateshead Dispensary, Nelson Street (built 1855), c1890.
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Top: Newgate Street, Morpeth, c1890. Bottom: Tynemouth, Northumberland, c1890.
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It is not known what type of education Andrew and his siblings received or the length of time it lasted, but it is clear that they were educated children, who would in later life make something of themselves. Andrews elder brother John Freeland Fergus Common was to make his career as an Iron Ship Builder and later on as a Naval Architect; whilst his younger sister Mary Jane married in 1878 Henry Austen Hensman a sanitary engineer from London. Tynemouth Shortly after her husbands death, Mary Common moved her family to the picturesque coastal town of Tynemouth to live with her younger brother George Hall, the manager of a local White Lead Works. It is possible that whilst living in Tynemouth, young Andrew renewed his acquaintance with the telescope he had grown fond of in Morpeth. John Pickering Bates its owner had by 1855 qualified as a surgeon, and had set up his practice at No. 15 Saville Street in Tynemouth. He later married in Tynemouth and continued working there as a surgeon until his retirement in about 1879, when he moved back to Morpeth. By the time of the 1861 Census Mary Common is found living at her brothers house at No. 8 Tynemouth Place, Tynemouth with her eldest son John and her daughter Mary Jane, but no sign of Andrew Ainslie Common. Gayton Andrew first known employment was working with his uncle Walter Hall. Sometime before 1850, Walter Hall, a baker by trade met a young lady called Mary Anne Matthews, the daughter of Robert Matthews a miller from the village of Gayton in Norfolk. Robert Matthews a widower had in 1845 married Andrews Aunt Margaret Chapman (nee Hall) the widow of Jasper John Chapman. Walter Hall married Mary Anne Matthews in 1850 and moved to Gayton. At the time of the 1851 census Walter Hall was listed as being a farmer employing 3 men, and his wife a miller employing 4 men. Ten years later in 1861, Walter Hall was running the Mill at Gayton, and Andrew Ainslie Common was employed there as a Miller. He was then 19 years old. It is not known when Andrew Common began working in Gayton, as a Miller, but it is likely to have been sometime after Walter Hall took over running the Mill from Robert Matthews, which was in 1853. It was whilst working at Gayton Mill that Andrew Ainslie Common learned the meaning of hard work, dedication and perseverance that were to
Appointment of Thomas Common as Surgeon at Gateshead Dispensary May 1842.
Tynemouth Place, Tynemouth.
Millers at Gayton Mill (1836 1937).
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become part of his character, and which he exhibited throughout the rest of his life. He was well known for both his great physical and mental strength, as well a great ability to enjoy life to the full. A number of examples of this were recounted in his obituary which appeared in the Observatory
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journal for 1903 written by Mr. Herbert Hall Turner. He was a strong man in all senses, and liked trying himself to the limit. He turned at the meeting the British Association in Bradford with his arm in a sling, because he had been trying whether could hold a bicycle out at arms length and had consequently ruptured a muscle. It was whilst he was working for his uncle that Andrew Common met Ann Matthews, the daughter of Abraham Matthews, a farmer and his wife Martha (nee Mason). They married on 18th July 1867 at St. Nicholas Church, Kings Lynn. It is known that by the time of their marriage Andrew had left Gayton a few years earlier to work for his other Uncle, Matthew Hall in his building material business in Marylebone, Middlesex. His uncle Walter Hall continued to work the Gayton Mill until 1872, but died shortly afterwards in 1875. Matthew Hall & Company Matthew Hall was a born entrepreneur. He had started his first business in Newcastle in the 1830s, where he earned a living as a builder, a cabinet maker and Joiner. Sometime before 1848 he moved to London, where he set up his plumbing business in that year. The London Post Office Directory for 1848 shows him listed as a Plumber at No. 11 Bulstrode Mews, Marylebone Lane, Middlesex, London. Andrew Common began working for him around 1865, and by the time of the 1871 we find him with his wife Ann and their one year old daughter Violet Mary, living at No. 17 South Bank, near Regents Park in London. On the Census Return he listed his occupation as an Engineer. In the coming years Matthew Hall grew to rely on his nephew more and more as his business expanded to become a well respected and highly profitable enterprise. On the death of Matthew Hall in 1878, the running of the business was left to Andrew Ainslie Common. As a result he had the money and the freedom to take up his passion for Astronomy once again. In 1874 he acquired his very first telescope, a 5 , Equatorially Mounted Refractor. It was with this instrument that he made his first attempts at photographing the heavens. Two years later on the 9th June 1876 he was elected a Fellow of the Royal Astronomical Society. His passion for Astronomy had not diminished and he was beginning to be recognised as someone who would make important contributions in the field. The other Fellows of the Royal Astronomical Society warmed to him not only for his ability but also for his larger than life personality. It was in their company that he felt
Gayton Mill in 1910 and in 2003.
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most comfortable and where he gained a number of lifelong friendships. This is evident by the warmth and affection leading astronomers like the Sir Frank Dyson, Henry Hall Turner and others had for him. Ealing In about 1876, Andrew Common moved from his house near Regents Park, to No. 63 Eaton Rise, Ealing, where he remained for the rest of his life. His occupation at this time was given as Electrical Engineer and Lead Manufacturer. The later cen-
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suses of 1891 and 1901 show the transition between Andrew Commons association with Matthew Hall & Co., and his passion for Astronomy. The 1891 Census gives his occupation as Building Contractor and Astronomer; whilst 10 years later his sole occupation has become that of a Telescope Maker and Employer of Workers. Sometime around 1890 Andrew Common had given up working for Matthew Hall to concentrate all his efforts towards the construction of telescopes. It is likely that Andrew Commons son Thomas took over the control of his great uncles company. Both the 1901 and 1911 Censuses states that his occupation was that of a Sanitary Engineer with the status of Employer. Thomas Andrew Common died in 1912, the year after the death of his mother Ann Common (nee Hall). Telescopes In 1877 Andrew Common decided to upgrade his equipment - a characteristic exhibited by almost every amateur astronomer. He purchased two 17 inch Glass Discs with the intention of grinding his own mirror and using them in a Reflecting Telescope of his own design. This idea was soon abandoned; instead he purchased an 18 inch Reflector from Mr. George Calver and attached it to a mount designed and constructed by him. He put his new instrument to good use and by the following year, he had communicated to the Royal Astronomical Society the results of his observations of the outer satellite of Mars (Deimos) and the satellites of Saturn; in a paper published in the Monthly Notices for January 1878. However it soon became apparent that Andrew Common wanted to use his new telescope for astrophotography. In the April 1879 edition of the Monthly Notices of the Royal Astronomical Society, he published two papers related to Astrophotography. The first entitled On the desirability of photographing Mars and Saturn at the next conjunction. In this paper which he presented to the society the following extract is of some importance: In the December 1878 Number of the Notices of this Society the particulars of the conjunction of Saturn and Mars on June 30, 1879, are given by the Astronomer Royal. I trust that those astronomers who can will take advantage of this excellent opportunity of testing the relative actinic intensity of light of the two planets. As they can then be taken under the same conditions, and if differently prepared plates are used - that is the ordinary wet plate and iodised collodion, and those dry plates that are more sensi-
Uncle of Andrew Common, Founder in 1848 Matthew Hall Engineering.
South Bank, Regents Park, St. Johns Wood, 1868.
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Eaton Rise, Ealing, c1910.
tive to the red rays - the different effects of the colours of the planets might be made apparent. Perfection of image would not be of so much importance as the effect in producing chemical ac-
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tion on the plate. To show the possibility of doing this, I beg to lay before the Society two photographic plates, one with a row of pictures of Jupiter (showing the effect of a slight difference in the exposure on the image both as to size and density), and the other a picture of Saturn, all taken with an exposure of about 2 seconds in the case of Saturn, and still less in the case of Jupiter, by an eighteen-inch silver-on-glass Newtonian telescope. March 1879 It therefore seems that by before March 1879 Andrew Common had used his 18 inch Reflector to obtain photographs of Jupiter and Saturn using Dry Gelatin Plates, and not the Wet Collodion plates (developed by Frederick Scott Archer). The photographs he obtained were too small to show any detail on the planets surface. His second paper of April 1879 dealt with a subject for which Andrew Common true claim to fame as a Great Astrophotographer lies - Note on Large Telescopes with suggestions for mounting Reflectors. In this paper he considers the mounting of Reflectors and how best such a mounting should be constructed. Having, then, by this process of selection got the silver-on-glass reflector on the Newtonian principle, it becomes necessary to consider the mounting; and here we come to what may be regarded as the vital point; for on the proper mounting of the reflector, so as to point it to any object in the heavens, and follow that object in its diurnal motion, while retaining all the conditions that are favourable to the best performance of the optical part, a great deal depends. As far as I know, no endeavour has been made to really find out these favourable conditions and make the mounting suit them, except in a partial manner. I have endeavoured to find them out, and propose to indicate how they ought to be attained. They are as follows: No tube properly so called; No mass of metal either below or at the side of the line joining the large and small mirrors; An equatorial mounting capable of direction to any part of the visible heavens, and of continued observation past the meridian without reversal; An efficient means of supporting the mirror without flexure; Driving clock. Circles to find or identify an object and conditions taken to eye end; A collimator for the ready adjustment of the mirrors; Such, a construction of mounting as to give the greatest mount of steadiness with the least amount of Motion; An effectual means of re-silvering the mirrors and of protecting them from dew; A safe, steady, and easily adjusted platform for observer, allowing about two hours' continuous observation without the necessity of any motion, except that from the observers place, and of ready access; A suitable locality for the erection of the telescope.
The suggestions made by Andrew Common in this paper are of fundamental importance and are instrumental to achieving success in Astrophotography. He was the first person to stress the need for a steady mount fitted with an accurate motor drive; and the need for well balanced and collimated optics free from flexure. Without these criteria being met the chances of obtaining well focussed photographs of any astronomical object are at best minimal. Andrew Common heeded his own advice and by July of 1879 he had obtained a new 37 inch mirror from George Calver, which he then mounted according to the principles he had outlined in his paper. The mounting he designed was a radical departure from the norm. It showed great engineering skill, and paid particular attention for the need to reduce friction between the moving parts. For example his design required the polar axis to be partly floated in mercury in order to reduce friction between adjacent surfaces. He also planned (but did not implement) for the use of an electric clock to accurately follow the movement of the stars caused by the diurnal motion of the Earth. With the 3-foot reflector Common made visual observations of the satellites of Mars and Saturn, and the nebulosity embedded in brightest stars of the Pleiades. In the Observatory Journal of 1880, Andrew Common published further photographs of Jupiter now taken with his new 3 foot reflector on the 9th September 1879. The Editor noted the following: We are Indebted to Mr. Common for the enlarged prints from photographs of Jupiter (Plate III.), taken with his magnificent 3-feet silver-on-glass reflector. Small though these photographs are, they give us much valuable information; and they have this great merit, as compared with the drawings of most observers, that they can be relied upon as accurate. It is little to the credit of those who attempt to make astronomical drawings, that a photograph less than 1/20th of an inch in diameter should be sufficient to expose the inaccuracies of drawings on 300 or 40 0 times the scale. In this
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Great Orion Nebula M42 Photographed by Andrew Common 1883.
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connexion we would invite our readers to compare Capt. Noble's representation of Jupiter in the ' Monthly Notices' for January with Mr. Common's photograph of Jupiter and the Red Spot. The photograph of Jupiter and his four satellites is important, as showing the relative brightness of the satellites He also obtained a photograph of a Comet on the 24th of June 1881, on the same night that it was photographed by Henry Draper in America. It was one of the earliest successful photographs of a comet. Andrew Common's energies with his new telescope were however mainly devoted to the imaging of the Great Orion Nebula (M42). His first attempt was on the 20th of January 1880, and was a total failure, but he patiently improved the driving of his clock and took advantage of each increase of sensitiveness in photographic plates till on the 17th of March 1882 he obtained a photograph "which excited the admiration of all the astronomers who had an opportunity of inspecting it. He still further perfected the guiding of his telescope, and obtained on the 30th of January 1883, with an exposure of 37 minutes, the splendid photograph with which all astronomers are familiar. Of the merits of this photograph he modestly remarked: "Although some of the finer details are lost in the enlargement sufficient remains to show that we are approaching a time when photography will give us the means of recording, in its own inimitable way, the shape of a nebula and the relative brightness of the different parts in a better manner than the most careful hand-drawings." He later on the 28th February 1883 obtained a photograph of M42 with a longer exposure of 60 minutes. In 1884 Andrew Common was awarded the Gold Medal of the Royal Astronomical Society for his work on Astrophotography and in particular his photographs of the Great Orion Nebula. Shortly after he received the Gold Medal he sold his 3 foot reflector to Mr. Edward Crossley, a Halifax businessman and passionate amateur astronomer. In the annual report of his Observatory at Ealing for the year 1884, Andrew Common remarks: During the past year a small number of celestial photographs have been taken, including two of the Dumb-bell nebula, and a number of experiments have been made in stellar photography. The 3-foot Reflector has passed into the hands of Mr. Crossley, of Halifax, at whose Observatory it is
36 inch Reflector at Ealing.
now erected. It is intended to replace this instrument with one of 5-foot aperture, made expressly for photography, with a mounting having for the polar axis a hollow iron cylinder floating in water, so as to reduce the friction and vibration of a merely mechanical mounting. The disk of glass for the large mirror was obtained in 1883, and seems to be all that can be wished for. It is apparent that shortly after he had successfully imaged the Great Orion Nebula in the March of 1882, he had been thinking about building an even larger reflecting telescope, and by the following year the plans for its construction were in place and the glass blank for his monster 60 inch reflector had been purchased. The construction of the 60 inch Reflector was to be the great work of his life into which he would put months and years of patient effort, hard work and great skill into its completion. The annual reports of Royal Astronomical Society on the work carried out by the observatories of its members provide valuable insight into the progress made by Andrew Common on the construction his 60 inch Reflector. Andrew Common wrote in his report on the Ealing Observatory for 1885: Experiments in stellar and astronomical photography with various kinds of telescopes have been made. The De La Rue polishing machine has been removed from the University Observatory, Oxford, and erected in the workshop, and a temporary mounting and house is in the course of erection for further experiments. A comet was found on the night of Friday, the 4th of September, and change of position noticed that evening. This proved to be a comet already found a few days before by Brooks in America. A series of observations were made on the Nova in Andromeda immediately after the announcement from Dun Echt.
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36 inch Crossley Reflector, Lick Observatory, Mount Hamilton, California.
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Schematic Drawing of the 5 foot Reflector.
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So during 1885 there was no apparent progress made on the construction of the 5 foot reflector apart from setting up the mirror polishing machine. The report for the year 1886 is more positive and indicates that considerable progress had been made: The last year has been entirely devoted to the construction of the 5-foot reflector. The machine for grinding was completed in September, and great progress has been made with the mirror. Photography has been used to obtain permanent records of the state of the surface by using the reflected light from a pinhole (illuminated by a lamp), as in the system of testing used by Foucault. It is found that so small a quantity of light as can come through a hole .004 inch placed at the centre of curvature can be photographed in a few seconds after reflection from the surface. A series of photographs have been taken from the first rough polish to the present state, and will be continued. The kind of mounting has been determined upon, and the heavy work put in hand. It is hoped that the whole may now be completed without further delay. The telescope is to be devoted to photography, and the mounting has been designed to give the greatest amount of steadiness and perfection of movement. The following years report for 1887 indicates that the construction of the telescope is nearing completion: Considerable progress has been made in the construction of the 5-ft. reflector. The mirror has been polished and figured several times in order to gain experience in the art. There is evidence of internal strain in the glass, which may or may not affect the image, and it is contemplated to order another disc in case this one does not permit of a good final figure. The mounting is in a forward state, the telescope tube being connected to the polar axis, this latter being a wrought-iron cylinder about eight feet diameter which will float in a tank of water, so as to relieve the friction in the manner mentioned in vol. xliv. of the Monthly Notices, p. 367. The house or covering for the telescope, which will also carry the platform for the observer when the telescope is used as a Newtonian, is framed together and partly erected. It is hoped that the whole will be ready to use in the autumn. The telescope was finally completed in the September of 1887, as stated in the report for 1888: The 5-foot reflector was practically completed last September, and is now ready for work. On the few occasions that the weather has permitted, some trial photographs have been obtained that show a very satisfactory advance on those taken in 1883 with the 3-foot. It is intended to devote this telescope to the direct photography of the more important nebulae and to spectroscopic work on such objects as can be best observed with such an aperture. The 6-inch achromatic is in good order. The transit instrument has been dismounted, and the room in which it stood used for a battery-room for two batteries of E.P.S. cells, available for lighting or power in the Observatory. In the making of the 5-foot mirror much work was done of an experimental character in order to acquire the art of working glass. Many kinds of grinding and polishing substances, both for tools and for grinding or polishing the surfaces were tried, as well as different lubricants and methods of testing. From the experience thus gained a definite plan of working and testing curved surfaces has been arrived at that is very certain, a mirror of 30 inches diameter having been since figured in a comparatively short time. In addition to the machine made for the 5-foots mirror, on which mirrors of smaller size can be figured, another machine has been erected for grinding and polishing mirrors under 30 inches, both curved and plane, with means for figuring mirrors of very short focus. It is intended to prepare some mirrors of about 20 inches diameter, with a view of finding the shortest focus that will work; as such mirrors might be of great use on nebulae, comets, and the corona during eclipse. However by the time of the next report for 1889, progress had been halted and if anything had gone backwards, as Andrew Common explains: The 5-foot mirror not being found on trial to be quite satisfactory, owing to the slight ellipticity of the image of a star, probably duo to the fact that the disc of glass had been resting in a sloping position for some years, was taken out in the spring and refigured and re-silvered; the image now given is very much better; owing to the very bad weather very little work has however been done with it yet. The 20-inch mirrors mentioned in the last, report have been made, and two of them sent out to the Eclipse of December 22. As far as trials made before they were sent enable one to judge, such short-focus mirrors are likely to be very efficient. One is now being erected for regular use in the house lately covering the 6-inch achromatic which has been dismounted.
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A new disc for the 5-foot telescope has been ordered and is expected shortly, as well as several discs of large size for plane mirrors. In view of the much better results that may be hoped for from the use of such piano mirrors as siderostats, particularly in eclipse and spectroscopic work in future, the making of plane mirrors of very large size is next to be taken up. After over four years of labour the 60 inch telescope was still not completed and a new mirror had to be ground. Finally during 1890 Andrew Common was able to use it for its intended purpose, although the new mirror had not been ground and the inclement English weather was as is usual a key factor in dampening any adventure requiring its cooperation: The weather during the past year has been very unfavourable for observation at Ealing. Advantage has been taken of every available night, but the 5foot telescope has only been in use 48 nights since March 1890, and only 24 of these were suitable for nebula photography. In all 31 photographs of nebulae and clusters have been obtained. The principal nebula photographs are Orion 6 (one with 2 hours 35 minutes exposure, and one with 2 hours' exposure on plates stained with erythrosin; the first mentioned is much the best hitherto obtained); the Dumb-bell nebula 5 (the best with 110 minutes exposure on July 24, showing a large amount of detail) ; M 77, 3 (one with 150 minutes exposure, showing the spiral structure very clearly); M 99, 2 (with exposures of 2 hours and 2 hours, with spiral structure clearly shown) ; M 96, 1 hour; M 88, 1 hour; M 59 and 60, 2 hours 5 minutes; Gen. Cat. 4045,2 hours; Gen. Cat. 2203, 2207, 2211, 1 hour; and the Pleiades, 1 hour; showing nebulae. Amongst the clusters photographed may be mentioned those of M 2 (four photographs) and of M 5 (four photographs), the latter showing some new variable stars near the cluster; see Monthly Notices, vol. 1., page 519, June 1890. Photographs of the Moon have been obtained on nine nights during the year, and Uranus and its satellites have been photographed on two occasions. Observations have been made of the satellites and general appearances of Saturn, Uranus, and Neptune whenever possible, the observations of Mimas being communicated to the Society in May 1890, and published in the Monthly Notices, vol. 1. Page 404. A double wire micrometer, with position-circle and electric light illumination, has been made for the 5foot telescope, and also a star spectroscope (which was supplied at the end of 1890) fitted with special apparatus for watching the slit during the long exposures necessary for photographing the spectra of nebulae. Up to the present time, owing to bad weather, only preliminary work on the Orion nebula has been possible with the spectroscope. The spectrum of this nebula has been observed on three occasions (the only three possible since November), but no new lines have been detected. As mentioned in the last report, the figure of the 5foot mirror is not perfectly satisfactory owing to a slight ellipticity of the star images seen under high magnification, this ellipticity being probably due to the fact that the disc of glass rested in a sloping position for some years. The new 5-foot disc has been obtained from France, and the grinding of this will be proceeded with at once. Both the grinding machines have been kept in constant work. A 36-inch mirror of 11 feet 3 inches focal length has been made for the Science and Art Department, South Kensington, and two 30-inch mirrors of the same focal length have also been finished, one of these being made with a spherical instead of a parabolic curve to be used in the testing of flat mirror surfaces. Another 30-inch parabolic mirror is now in hand and nearly finished. Two 20-inch mirrors of 45 inches focal length have also been finished during the year, and have been thoroughly tested in the 20-inch telescope erected in place of the 6-inch refractor. A series of photographs of the Pleiades, the Dumb-bell nebula, of various clusters, and several photographs of the Andromeda nebula were taken with this telescope during the testing of the 20-inch mirrors, but the photographs have not yet been compared and measured. An instrument for rapidly comparing and measuring photographs, as described in the "Observatory," in August 1890, is almost completed, and will be used for a full examination of these photographs as well as for those taken with the 5-foot reflector. A long series of experiments on the photographic determination of the reflecting power of silver, speculum metal, and silvered-glass surfaces (prepared by different silvering processes), and on the reflecting and transmitting power of plain glass have been carried on, but are not yet completed. The results will be communicated to the Society as soon as the experiments are concluded. A number of trials have also been made of various silvering processes, and a new process has been adopted by means of which a perfect film of any required thickness can be formed with absolute certainty, and mirrors of any size can be silvered with ease and rapidity.
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The scarcity of good nights, partly due to the nearness to London, limits the use of the large telescope very much, and it is in contemplation to remove it to some more suitable position. The above account given by Andrew Common clearly shows that his new telescope was beginning to become useful, and had been used to take photographs of a number of the more well known Deep Space Objects; exactly the sort of targets the modern imager would choose - the Dumbbell Planetary Nebula M27 in Lyra; the Seyfert Galaxy M77 in Cetus; the Pleiades Cluster M45 with its embedded nebulosity; and the Globular Clusters M2 in Aquarius and M5 in Serpens Caput. He was however becoming concerned about the suitability of the telescopes location near to the London metropolis - he had taken note of the advice given in item No. 10 of his paper of April 1879. The year 1890 was the best the telescope was to see during Andrew Commons lifetime, for the report given to the Royal Society in 1891 was in stark contrast to the one given the previous year: During the past year a new 5-foot mirror has been made for the telescope. This piece of glass has proved to be almost if not quite - perfect, and the mirror is a most excellent one. Some very fine photographs of nebulae and the Moon have been taken, that will be laid before the Society. A new grating spectroscope has been fitted to the 5-foot. Work on plane mirrors has been carried on in the workshop. That was all he said and the telescope was never used again, why? There a number of factors why this proved to be the case. Firstly, it is known that Andrew Common narrowly escaped a fall from a high platform when he was using the telescope as a Newtonian Reflector. This must have shocked him as such a fall could easily have proved fatal. He made some attempts to convert the telescope to a Cassegrain system, but the prospect of drilling a hole through the centre of the mirror he had spent so much time on - seemed not to be a good idea. An attempt was made to avoid this catastrophe in the waiting by devising a system where the secondary mirror was inclined so that the image was clear of the primary mirror. Despite some initial success the method proved unsatisfactory and Andrew Common abandoned the idea altogether and the telescope he had lived with for so long. Secondly, the reports he prepared during the years the 60 inch reflector was undergoing construction, showed that it was not the only project with which Andrew Common was involved in. He was making
mirrors for other people and for other projects. Not only that, but he gave generously of his time, expertise and money. If someone wanted a mirror made, Andrew Common obliged. For example he made two 20 inch mirrors for the Solar Eclipse of 1889, which he presented to the Royal Society; two 16 inch mirrors for the eclipse expedition of 1896 followed; as did a 30 inch mirror for the Solar Physics Observatory and in 1900 a 20 inch mirror for the National Physical Laboratory. The additional effort required to complete these extra projects must have had a delaying affect on completion of his 60 inch telescope. Thirdly, the concerns Andrew Common had for the sighting of his 5 foot reflector amid the ever increasing glow of nearby London must have weighed heavily on his mind, as must the poor weather England always faced! After his death the telescope was sold to Harvard College Observatory and later sent to Bloemfontein in South Africa. However, the final reason for abandoning the 5 foot reflector was that Andrew Common found something to do which he considered more important. Andrew Common became interested in developing telescopic gun sights for use by the Army and the Royal Navy. His knowledge of optics together with his great practical skills made him the ideal person to successfully see such a project to fruition. It is not known how he became involved in such a project, but it was in his nature to do something for the common good and not just for himself. As regards its national importance the following words of Captain Percy Scott, R.N., spoken at a dinner at the Savage Club on 22nd of November 1902, will suffice: "The nation owed a deep debt of gratitude to Dr. Common for the great improvements that he had made in gun-sights. It mattered not how good the gun was, nor how good a man there was behind it; unless the sight was perfect good firing could not be made. The great stride by the British Navy lately in that direction was entirely due to Dr. Common. ... He had produced a telescope gunsight which would, when properly used, quadruple the fighting efficiency of our battleships. Andrew Ainslie Common died suddenly of a heart attack in his study at No. 63 Eaton Rise, Ealing on the 2nd June 1903; he was nearly 62 years old. He was survived by his widow Ann (1840-1911) and their four children - Thomas Andrew Common (1875-1912), Violet Mary Common (1869-1952), Lillian Martha Common and Ida Common (18801951). He will be remembered not only for his magnificent
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Andrew Commons 60 inch Reflector, at Harvard College Observatory, c1910.
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60 inch Reflector, Boyden Observatory, Bloemfontein, South Africa.
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images of the Great Orion Nebula, but more importantly for the guidelines he laid down for achieving successful astronomical images and of course the two great reflectors he had spent so many years of hard effort in their construction. It is fitting and entirely appropriate that these two telescopes are not only still in use but are in Andrew Commons own words situated in a suitable locality for the erection of the telescope amid clear dark skies - now far away from the cloudy nights in Ealing where they first saw the occasional light of the stars - which so lit up the life of their creator. Notes on Andrew Common's Two Great ReflectingTelescopes 36 inch Reflector In 1884 Common sold his 36-inch reflecting telescope to Edward Crossley of Halifax, Yorkshire, England. The weather in Halifax proved totally unsuitable for a telescope of this size and little use was made of it. As a result Edward Crossley donated the telescope to the Lick Observatory shortly after his retirement from astronomy in 1893. The Crossley 36-inch reflector at the Lick Observatory was the first of a long line of metal-film-on-glass modern reflecting telescopes that have dominated major astronomical advances for the past century. In addition, the Crossley has produced more scientific results than any other telescope of its size, including several historically important studies in stellar evolution, the structure and spectra of planetary nebulae, and the discovery and spectral analysis of faint variable stars in young clusters. The Crossley also contributed to studies that confirmed the expansion of the universe. Within a short time the Crossley reflector was put to good use when James E. Keeler initiated a program of nebular photography with it. Keeler's photographs showed the existence of hundreds of spiral nebulae that are now known as galaxies. Neither Keeler nor anyone else at the time realized that nebulae were predominantly extragalactic, but Keeler, using Crossley photographs, was the first to realize that these objects were a major constituent of the universe. After Keeler's death, astronomer Charles Dillon Perrine completed Keeler's observational program, and in 1908 published a remarkable selection of Crossley photographs in memory of Keeler. Keeler's and Perrine's success with the Crossley reflector was probably more influential than any other single factor in convincing professional astronomers of the practical effectiveness of large reflectors. By the early 1900s, as a result of Keeler's and Perrine's work with the Crossley, it was apparent that the future of large telescopes lay with mirrors rather than lenses. A few years later, when George Ellery Hale began to plan for the establishment of a large observatory on Mount Wilson in California, the use of a large refracting telescope was not even considered. The Crossley had shown the way to the future of astronomy. Large reflecting telescopes would now dominate 20th-century astronomy. The Crossley 36-inch reflector is found a few hundred yards southwest of the Main Observatory Building of the Lick Observatory and is still in use as an operational scientific instrument for the study of the stars and galaxies. The Crossley 36-inch reflecting telescope, at the Lick Observatory, marked the first modern application of a reflecting telescope to astronomical studies. 60 inch Reflector Shortly after his death Andrew Commons 60 inch Reflector was purchased in 1904 for the Harvard University Observatory, by its Director Edward Charles Pickering. He intended to continue using it for the Harvard photometry survey down to as faint stars as possible with the instrument. It was found that the definition was far from satisfactory, and in fact very little use was indeed made of it as around that time there occurred the rapid development of photographic stellar photometry, making visual techniques less attractive. However, Harlow Shapley who became Director at the Harvard College Observatory in 1921 required access to a large telescope to further his researches on the limits of the visible universe. The telescope was refurbished and sent to the Harvards Boyden Station in Bloemfontein, South Africa. It became fully operational in 1933. The funds for the renovation had been obtained from the Rockefeller family, and the telescope was renamed the Rockefeller Telescope. The Rockefeller Telescope had an inauspicious start to life, but following its move to the Boyden Observatory it began to become useful, befitting a telescope with a 60 mirror. It is still in use today and actively participates in collaborative research projects with other astronomical institutions.
Bibliography
Stefan Hughes can be reached via email: contact@artdeciel.com Visit his home page with great stuff to history of astrophotography http://www.artdeciel.com/Exposure/ and his blog for astrophotographers: http://www.artdeciel.com/
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2.75 English Brass Refracting th Telescope, Late 18 Century
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Descriptions: A superb English brass refracting telescope with original tripod stand. Measurements: height - 51 cm, width/length - 98 cm, diameter - 7 cm. Credit: R. Jorgensen Antiques
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Credit: R. Jorgensen Antiques
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3 EnglishTableReflectingTelescope, th 18 Century
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Descriptions: A fine reflecting late 18th century (1785) shagreen covered telescope in the manner of Adams, in working order. Measurements: height - 36 cm, width/length - 46, diameter - 8 cm. Credit: Hansord Antiques
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Credit: Hansord Antiques
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In May 2012 was published Charles Rydel's book "Design and construction of telescopes and astrographs for amateurs" with a preface by J. C. Pecker, astronomer, member of the Academy of Science and Honorary Professor at the College de France. You will find his book in bookstores (for example Amazon). In about 500 pages, this book brings together the work of well-known amateurs. They deliver all the secrets of their achievements. This book is structured into five main chapters: 1) Optical Design with the software OSLO. 2) Construction and use of machinery to cut and polish the mirrors. 3) Testing an telescope objective (interferometry, self Foucault) 4) Travel telescopes and large amateur telescopes 5) Amateur instruments to study the sun.
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Shop: Affilate: Flip Book: eBook:
http://www.catchersofthelight.com/shop/ http://www.catchersofthelight.com/shop/affiliates.aspx http://www.catchersofthelight.com/eBookIntroduction.aspx http://www.catchersofthelight.com/eBooks/B.0_CatchersoftheLight_Introduction_eBook.pdf
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About the Author

Stefan Hughes has been observing the night sky since he was 12 years old, when he got his first telescope a small 3.5" Reflector, which was in his own words 'pretty useless'. He then got his first serious telescope three years later - a 6" (15cm) equatorially mounted Newtonian Reflector, which he used to look mainly at the moon and planets. He was so taken with Astronomy that he decided to make it his career, though ironically becoming a theoretical astronomer specializing in the field of Celestial Mechanics, being a student of Desmond King-Hele and the late Andre Deprit. In 1978 he was awarded a PhD for his thesis on the motion of Artificial Earth Satellites, which was published as a series of papers in the Proceedings of the Royal Society. After spells as a Research Fellow and University Lecturer he moved into the world of Computers when work became scarce in Astronomy, as a software designer and later project manager. During this time he drifted out of Astronomy, concentrating on his career and raising a family. He also had a further career change and spent five year training to become a Genealogist and Architectural Historian; which he practiced professionally for a number of years. In 2001 he moved to the island of Cyprus with his wife, and is now semi-retired devoting the majority of his time to his rekindled enthusiasm for Astronomy and in particular to Deep Sky Astrophotography, and of course the 'Art de Ciel' website. He is currently writing two books one on the history of astrophotography called Catchers of the Light and the second a biography with the photographic historian Dr. Marcel Safier on the Victorian Photographer Frederick Scott Archer entitled To the Sons of the Sun.
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Publish your articles on the ATM Letters Journal

Publishing an article on the ATMLJ is completely free. We are keen to receive original papers, articles and case studies on any relevant telescope making topic. Here is no limitation on the article pages or number of photos. There are no deadlines. Articles are run in the order received, so the sooner you submitted them in the sooner they will appear in print. The biography provided will be used to credit the author; with links made to your website and email address where provided. Although we cannot make payments for articles published, we do donate you with a free copy of the current issue where your article was published. Submit your article now and make your experience public to over 100 ATMLJ reader, all advanced amateur astronomers and telescope makers.
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Available in October 2012
In the next Issue of ATM Letters
William Usherwood (1821-1915)

The Comet Man
William Usherwood a commercial photographer from Walton-on-the-Hill, Surrey, England, took the first ever photograph of a comet when he captured Donatis comet from nearby Walton Heath, Surrey on the 27th September 1858, beating George Phillips Bond from Harvard Observatory by a night! Unfortunately, the photograph taken by Usherwood has been lost...
ATMLJ 10 Anniversary Gift Beautiful Jupiter Satellites Widget
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July/August Issue, 2012

ATM Letters July/August Issue, 2012

ATM Letters Journal

ATM Letters July/August Issue, 2012

ATM Letters Journal

ATM Letters July/August Issue, 2012

ATM Letters Journal

ATM Letters July/August Issue, 2012

Issue July/August | Volume 10 | Number 4

Vertical Direct North/South Sundial

23 Troughton & Simms Dividet-Lens Double Image Micrometer

Study of the motions of artificial satellites and space vehicles

Globular Cluster and Cyber Sky

MODAS NG Update Mirror Testing

COMPUTER AND TELESCOPES

History Andrew Ainslie Common: The Common Man

ADVERISEMENTS NEXT ISSUE

ATMLJ 10 Anniversary Looking back Moving Forward

ATM Letters July/August Issue, 2012

gift_moonphasewgl.zip Large Moon Phase widget by Ivan Krastev

e-Articles, e-Books us_patents.zip - Patent, - Patent, - Patent, - Patent, - Patent, ebooks.zip

ATM Letters July/August Issue, 2012

For new Readers

ATM Letters July/August Issue, 2012

For new Readers

ATM Letters July/August Issue, 2012

ATMLJ 10th Anniversary - Looking Back, Moving Forward

ATM Letters July/August Issue, 2012

ATM Letters July/August Issue, 2012

ATM Letters July/August Issue, 2012

ATMLJ 10 Anniversary Gift Beautiful Large Moon Phase Widget

ATM Letters July/August Issue, 2012

Spectrum - RoboScopes - Real Armchair Astronomy

RoboScopes - Real Armchair Astronomy

RoboScopes - Real Armchair Astronomy

RoboScopes - Real Armchair Astronomy

The Liverpool Telescope. Credit: Liverpool Telescope/R. Smith

ATM Letters July/August Issue, 2012

RoboScopes - Real Armchair Astronomy

RoboScopes - Real Armchair Astronomy

Global Rent-A-Scope interface

RoboScopes - Real Armchair Astronomy

RoboScopes - Real Armchair Astronomy

RoboScopes - Real Armchair Astronomy

(Source: Universe Today/Nick Howes)

Comet C/2007 Q3 (Faulkes Telescope)

Credit: Nick Howes

The LT open at sunset. Credit: Liverpool Telescope/A. Gomboc

ATM Letters July/August Issue, 2012

Praxis - Vertical Direct North/South Sundial by Carl Sabanski

Vertical Direct North/South Sundial

ATM Letters July/August Issue, 2012

Vertical Direct North/South Sundial

Table 1. Hour Line Angle Calculations for direct north sundial.

Table 2. Hour Line Angle Calculations for direct south sundial.

ATM Letters July/August Issue, 2012

Vertical Direct North/South Sundial

Vertical Direct North/South Sundial

Figure 3: Vertical sundial with gnomon 5 units high .