International Journal of Continuing Engineering Education and Lifelong Learning, 2007
... p.3) goes as far as stating that the technological dimension cannot be separated from the co... more ... p.3) goes as far as stating that the technological dimension cannot be separated from the contextual dimension. The extent to which context is formed by technology and text (as language) the means for interaction, forms the basis for our examination of online multiculturalism. ...
Proceedings of The National Academy of Sciences, 2004
Ghrelin is a recently identified growth hormone (GH) secretogogue whose administration not only i... more Ghrelin is a recently identified growth hormone (GH) secretogogue whose administration not only induces GH release but also stimulates food intake, increases adiposity, and reduces fat utilization in mice. The effect on food intake appears to be independent of GH release and instead due to direct activation of orexigenic neurons in the arcuate nucleus of the hypothalamus. The effects of ghrelin administration on food intake have led to the suggestion that inhibitors of endogenous ghrelin could be useful in curbing appetite and combating obesity. To further study the role of endogenous ghrelin in appetite and body weight regulation, we generated ghrelin-deficient (ghrl-/-) mice, in which the ghrelin gene was precisely replaced with a lacZ reporter gene. ghrl-/- mice were viable and exhibited normal growth rates as well as normal spontaneous food intake patterns, normal basal levels of hypothalamic orexigenic and anorexigenic neuropeptides, and no impairment of reflexive hyperphagia after fasting. These results indicate that endogenous ghrelin is not an essential regulator of food intake and has, at most, a redundant role in the regulation of appetite. However, analyses of ghrl-/- mice demonstrate that endogenous ghrelin plays a prominent role in determining the type of metabolic substrate (i.e., fat vs. carbohydrate) that is used for maintenance of energy balance, particularly under conditions of high fat intake.
The cancer chemotherapeutic agent Taxol (paclitaxel) causes a dose-related peripheral neuropathy ... more The cancer chemotherapeutic agent Taxol (paclitaxel) causes a dose-related peripheral neuropathy in humans. We produced a dose-dependent large-fiber sensory neuropathy, without detrimental effects on general health, in mature rats by using two intravenous injections 3 days apart. Tests of other dosing schedules demonstrated the dependence of the severity of the neuropathy and of animal health on both the dose and the frequency of dosing. Pathologically, severe axonal degeneration and hypomyelination were observed in sections of dorsal roots, whereas ventral roots remained intact. Electrophysiologically, H-wave amplitudes in the hindlimb and amplitudes of predominantly sensory compound nerve action potentials in the tail were reduced. These effects persisted for at least 4 months after treatment. Motor amplitudes were not affected, but both motor and sensory conduction velocities decreased. The ability of rats to remain balanced on a narrow beam was impaired, indicating proprioceptive deficits. Muscle strength, measured by hindlimb and forelimb grip strength, and heat nociception, measured by tail-flick and hindlimb withdrawal tests, were not affected by Taxol. This model of Taxol-induced neuropathy in mature rats, with minimal effects on general health, parallels closely the clinical syndrome observed after Taxol treatment in humans.
Systemic administration of brain-derived neurotrophic factor (BDNF) decreases nonfasted blood glu... more Systemic administration of brain-derived neurotrophic factor (BDNF) decreases nonfasted blood glucose in obese, non-insulin-dependent diabetic C57BLKS-Lepr(db)/lepr(db) (db/db) mice, with a concomitant decrease in body weight. By measuring percent HbA1c in BDNF-treated and pair-fed animals, we show that the effects of BDNF on nonfasted blood glucose levels are not caused by decreased food intake but reflect a significant improvement in blood glucose control. Furthermore, once established, this effect can persist for weeks after cessation of BDNF treatment. Oral glucose tolerance tests were performed to examine the effects of BDNF on blood glucose control in the fasted state and after an oral glucose challenge. BDNF treatment normalized fasting blood glucose from initially hyperglycemic levels and also showed evidence for beneficial, although less marked, effects on the ability to remove exogenous glucose from blood. One means to lower fasting blood glucose is to reduce the glucose output of peripheral tissues that normally play a part in the maintenance of fasting hyperglycemia. Because the liver is the major endogenous source of glucose in blood during fasting, and because hepatic weight and glucose output are increased in type 2 diabetes, we evaluated the effects of BDNF on liver tissue. BDNF reduced the hepatomegaly present in db/db mice, in association with reduced liver glycogen and reduced liver enzyme activity in serum, supporting the possible involvement of liver tissue in the mechanism of action for BDNF.
In July 2007 we began a intensive program of physical characterization of planetary radar targets... more In July 2007 we began a intensive program of physical characterization of planetary radar targets at the Palomar Mountain 200-inch Hale Telescope (P200) and the JPL Table Mountain Observatory 0.6-m telescope (TMO), collecting CCD spectra, BVRI colors and R-band lightcurves of essentially all radar targets observable from the northern hemisphere. Radar observations benefit greatly from optical observations, especially rotational lightcurves and taxonomic classification. We also seek to characterize Potentially Hazardous Asteroids (PHA: MOID ≤ 0.05 AU, H ≤ 22.0 mag) and low-ΔV (LDV: ΔV ≤ 6.29 km/s) near-Earth asteroids as they become available from our latitude. Between January 2009 and July 2010 we acquired data on 38 objects over 107 nights at TMO and 28 objects over 8 nights at P200. We will report our spectra, colors, and light-curve photometry for the following minor planets, with the taxonomic classification (Bus Taxonomy) derived from our data listed in parenthesis: 1991 AQ10 (Sq), 1991 DB (C), 1994 CC (Sq), 1996 EN (V), 1996 FG3 (C), 1998 CS1 (Sa), 1998 FW4 (Xc), 1998 OR2 (Xk), 1999 AP10 (Sa), 1999 AQ10 (S), 1999 LF6 (L), 1999 MN (Sq), 2000 TO64 (S), 2000 UJ1 (S), 2000 XK44 (S), 2001 CV26 (S), 2001 FE90 (A), 2001 FM129 (Sq), 2002 VY95 (C), 2003 EF54 (V), 2003 QO104 (S), 2003 YT1 (R), 2004 FG11 (V), 2005 CW25 (T), 2005 EK70 (Sq), 2005 YU55 (C), 2006 AS2 (C), 2007 MK13 (C), 2008 EE5 (Sl), 2008 EV5 (C), 2008 SV11 (CX), 2009 KC3 (CX), 2009 KD5 (L), 2009 OG (S), 2009 UD2 (S), 2009 UN3 (S), 2009 UV18 (Ld), 2010 GU21 (X), 3554 Amun (X), 4486 Mithra (S).
The Near-Earth Asteroid (NEA) 4055 Magellan was discovered by Glo Helin at Palomar Mountain (IAUC... more The Near-Earth Asteroid (NEA) 4055 Magellan was discovered by Glo Helin at Palomar Mountain (IAUC 4638) and was one of the first known minor planets with surface reflectance properties comparable to that of 4 Vesta (Tholen, 1988). Broad-band photometry and near-IR spectroscopy revealed strong 0.9 and 1.9 micron proxene bands, suggesting a compositional similarity of 4055 Magellan with that of 4 Vesta and the basaltic achondrite meteorites (Cruikshank et al. 1991). In anticipation of the Dawn mission to 4 Vesta we obtained 5 partial nights, 2010 August 9/10/12/13/14, of Bessel R photometry of 4055 Magellan at the Jet Propulsion Laboratory Table Mountain 0.6-m telescope (TMO). We measured a synodic period of 7.488+/-0.001 hr, similar to the 7.475+-0.001 hr period obtained by Pravec et al. (http://www.asu.cas.cz/ ppravec/newres.txt). Our object exhibited a large lightcurve amplitude (delta_M 0.8 mag) implying a highly elongated shape. We used our TMO photometry and the absolute magnitude as tabulated by the Minor Planet Center to construct a rudimentary solar phase curve. We derived a phase parameter g=0.30, similar to the phase behavior as measured by Pravec and colleagues (http://www.asu.cas.cz/ ppravec/neo.html). Our high g implies a shallow solar phase slope, consistent with the object's high albeldo (rho=0.31) obtained from thermal measurements (Delbo et al. 2003). The photometric properties of the V-type 4055 Magellan , such as shallow phase slope and high albedo, are consistent with 4 Vesta, giving us confidence in using NEA vestoids as photometric analogs for 4 Vesta.
The Near-Earth Object (NEO) 2002 VE68 was discovered by the LONEOS Survey on November 11, 2002 (M... more The Near-Earth Object (NEO) 2002 VE68 was discovered by the LONEOS Survey on November 11, 2002 (MPEC 2002-V52). With a semi-major axis of 0.723 AU, 2002 VE68 is in a 1:1 mean motion resonance with Venus and can be considered a quasi-satellite of the planet. Orbital integrations by Mikkola et al. (2004) suggest that 2002 VE68 was likely an NEO injected into its current orbit by a close Earth encounter approximately 7000 years ago and will remain a Venusian quasi-satellite for another 500 years. This object has been designated a Potentially Hazardous Asteroid by the Minor Planet Center. We took advantage of the object's 2010 apparition to collect rotationally resolved Bessel BVRI photometry over the course of three nights (November 10/12/13 2010) using the JPL Table Mountain 0.6-m telescope near Wrightwood, California. The object's mean colors (B-R=1.106+/-0.019 mag; V-R=0.419+/-0.021 mag; R-I=0.348+/-0.014 mag) are most compatible with an X-type spectral classification (Bus Taxonomy). A slight reflectance dip at 0.55 micron is consistent with the deep 0.50 micron feature observed in the spectrum of the E-type asteroid 2867 Steins (Weissman et al. 2008). The spectral resolution that our BVRI photometry affords is often insufficient to resolve the E-M-P sub-classes within the X-spectral complex (Tholen Taxonomy; Zelner et al. 1985). After converting the photometry from magnitude to flux units, we found a best-fit synodic period P_syn = 13.50+/-0.01 hr. Our photometry yields an absolute magnitude H_v=20.59+/-0.02 mag, implying an effective diameter D 200m (rho=0.25). The lightcurve amplitude of 2002 VE68 ( 0.9 mag) suggests that it may be a contact binary.
2009 KD5 was discovered May 26 2009 by the Observatorio Astronomico de Mallorca LSSS (La Sagra Sk... more 2009 KD5 was discovered May 26 2009 by the Observatorio Astronomico de Mallorca LSSS (La Sagra Sky Survey) Near-Earth Object (NEO) survey (MPEC 2009-K55) and identified as a Potentially Hazardous Asteroid (PHA) by the Minor Planet Center. The object's 2010 closest approach to the Earth is quite distant (delta=0.24 AU on June 29 2010). However, the apparition allows the NEO to be observed under slowly varying illumination and viewing geometry.
2009 KD5 was discovered May 26 2009 by the Observatorio Astronomico de Mallorca LSSS (La Sagra Sk... more 2009 KD5 was discovered May 26 2009 by the Observatorio Astronomico de Mallorca LSSS (La Sagra Sky Survey) Near-Earth Object (NEO) survey (MPEC 2009-K55) and identified as a Potentially Hazardous Asteroid (PHA) by the Minor Planet Center. The object's 2010 closest approach to the Earth was quite distant (delta=0.24 AU on June 29 2010). However, the 2010 apparition allows the NEO to be observed under slowly varying illumination and viewing geometry. We have analyzed six nights of Bessel BVRI observations at the JPL Table Mountain Observatory (TMO) 0.6-m telescope (6/15, 6/16, 6/19, 6/20, 7/03, 7/04 UT). The PHA's averaged broad-band colors (B-R=1.300+/-0.034 mag; V-R=0.491+/-0.027 mag; R-I=0.409+/-0.027 mag) were found to be most compatible with an L-type spectral classification (Bus & Binzel 2002). L-types asteroids are members of the S-family of asteroids and may represent surfaces highly processed by collisional gardening and space weathering. A solar phase curve constructed from our data was consistent with an assumed solar phase parameter g=0.15, yielding an Absolute Magnitude HV = 18.39 mag. Systematic departures in the night-to-night rotationally phase photometry suggested that the NEO is a binary asteroid. We have fit a two-period model for the lightcurve of 2009 KD5, with the primary P1 = 2.52 hr (very near the rotational break-up speed of a self-gravitating rubble pile) and secondary, presumably tidally-locked, component P2 = 21.7 hr. We have an additional two nights of unreduced photometry that should further constrain the asteroid's solar phase and rotational properties.
The near-Earth asteroid 66146 (1998 TU3) was discovered on 1998 October 13 by the LINEAR NEO surv... more The near-Earth asteroid 66146 (1998 TU3) was discovered on 1998 October 13 by the LINEAR NEO survey (MPEC 1998-U03). We obtained five nights of Bessel BVRI observations (2010 Aug 6,7,10,12,13 UT) and one night of Bessel R (August 8 PST) at the JPL Table Mountain Observatory (TMO) 0.6-m telescope near Wrightwood, California. These observations were obtained as part of our ongoing survey at TMO of Potentially Hazardous Asteroids (PHAs), planetary radar targets, and low delta-V near-Earth asteroids (NEOs). The object's rotationally averaged colors (B-R=1.238+/-0.011 mag; V-R=0.440+/-0.008 mag; R-I=0.275+/-0.010 mag) were found most compatible with an Sk-type spectral classification (Bus Taxonomy)/S-type (Tholen Taxonomy). This association was obtained through a comparison of our colors with the 1341 asteroid spectra in the SMASS II database (Bus & Binzel 2002). Our classification differs significantly from the Q-type taxonomy reported by Whitely (2002). Assuming a solar phase parameter g=0.15 we performed a period search using standard Fourier techniques. We found a best-fit rotational period Psyn=2.378+/-0.001 hr, in excellent agreement with the 2.3779+/-0.0004 period determined by Richards et al. (2007). The dispersion in the phased single period lightcurve strongly suggests that 1998 TU3 is be a binary system, with variations in observed flux caused by an unresolved, tidally locked secondary companion. Fitting a 2-period model as described by Pravec et al. (2000), we found that our photometry agrees well with a binary model (P1=2.378+/-0.01 hr, P2=28.28+/-0.05 hr). We have three additional nights scheduled for this object at TMO (Oct 8, 9, 10 2010 UT), extending our solar phase coverage and allowing us to refine our rotational models. 1998 TU3 will experience an exceptional apparition in 2012. This object may be a good candidate for shape/pole modeling via lightcurve inversion, especially if photometry can be obtained from both northern and southern hemispheres. We welcome any potential collaborations.
International Journal of Continuing Engineering Education and Lifelong Learning, 2007
... p.3) goes as far as stating that the technological dimension cannot be separated from the co... more ... p.3) goes as far as stating that the technological dimension cannot be separated from the contextual dimension. The extent to which context is formed by technology and text (as language) the means for interaction, forms the basis for our examination of online multiculturalism. ...
Proceedings of The National Academy of Sciences, 2004
Ghrelin is a recently identified growth hormone (GH) secretogogue whose administration not only i... more Ghrelin is a recently identified growth hormone (GH) secretogogue whose administration not only induces GH release but also stimulates food intake, increases adiposity, and reduces fat utilization in mice. The effect on food intake appears to be independent of GH release and instead due to direct activation of orexigenic neurons in the arcuate nucleus of the hypothalamus. The effects of ghrelin administration on food intake have led to the suggestion that inhibitors of endogenous ghrelin could be useful in curbing appetite and combating obesity. To further study the role of endogenous ghrelin in appetite and body weight regulation, we generated ghrelin-deficient (ghrl-/-) mice, in which the ghrelin gene was precisely replaced with a lacZ reporter gene. ghrl-/- mice were viable and exhibited normal growth rates as well as normal spontaneous food intake patterns, normal basal levels of hypothalamic orexigenic and anorexigenic neuropeptides, and no impairment of reflexive hyperphagia after fasting. These results indicate that endogenous ghrelin is not an essential regulator of food intake and has, at most, a redundant role in the regulation of appetite. However, analyses of ghrl-/- mice demonstrate that endogenous ghrelin plays a prominent role in determining the type of metabolic substrate (i.e., fat vs. carbohydrate) that is used for maintenance of energy balance, particularly under conditions of high fat intake.
The cancer chemotherapeutic agent Taxol (paclitaxel) causes a dose-related peripheral neuropathy ... more The cancer chemotherapeutic agent Taxol (paclitaxel) causes a dose-related peripheral neuropathy in humans. We produced a dose-dependent large-fiber sensory neuropathy, without detrimental effects on general health, in mature rats by using two intravenous injections 3 days apart. Tests of other dosing schedules demonstrated the dependence of the severity of the neuropathy and of animal health on both the dose and the frequency of dosing. Pathologically, severe axonal degeneration and hypomyelination were observed in sections of dorsal roots, whereas ventral roots remained intact. Electrophysiologically, H-wave amplitudes in the hindlimb and amplitudes of predominantly sensory compound nerve action potentials in the tail were reduced. These effects persisted for at least 4 months after treatment. Motor amplitudes were not affected, but both motor and sensory conduction velocities decreased. The ability of rats to remain balanced on a narrow beam was impaired, indicating proprioceptive deficits. Muscle strength, measured by hindlimb and forelimb grip strength, and heat nociception, measured by tail-flick and hindlimb withdrawal tests, were not affected by Taxol. This model of Taxol-induced neuropathy in mature rats, with minimal effects on general health, parallels closely the clinical syndrome observed after Taxol treatment in humans.
Systemic administration of brain-derived neurotrophic factor (BDNF) decreases nonfasted blood glu... more Systemic administration of brain-derived neurotrophic factor (BDNF) decreases nonfasted blood glucose in obese, non-insulin-dependent diabetic C57BLKS-Lepr(db)/lepr(db) (db/db) mice, with a concomitant decrease in body weight. By measuring percent HbA1c in BDNF-treated and pair-fed animals, we show that the effects of BDNF on nonfasted blood glucose levels are not caused by decreased food intake but reflect a significant improvement in blood glucose control. Furthermore, once established, this effect can persist for weeks after cessation of BDNF treatment. Oral glucose tolerance tests were performed to examine the effects of BDNF on blood glucose control in the fasted state and after an oral glucose challenge. BDNF treatment normalized fasting blood glucose from initially hyperglycemic levels and also showed evidence for beneficial, although less marked, effects on the ability to remove exogenous glucose from blood. One means to lower fasting blood glucose is to reduce the glucose output of peripheral tissues that normally play a part in the maintenance of fasting hyperglycemia. Because the liver is the major endogenous source of glucose in blood during fasting, and because hepatic weight and glucose output are increased in type 2 diabetes, we evaluated the effects of BDNF on liver tissue. BDNF reduced the hepatomegaly present in db/db mice, in association with reduced liver glycogen and reduced liver enzyme activity in serum, supporting the possible involvement of liver tissue in the mechanism of action for BDNF.
In July 2007 we began a intensive program of physical characterization of planetary radar targets... more In July 2007 we began a intensive program of physical characterization of planetary radar targets at the Palomar Mountain 200-inch Hale Telescope (P200) and the JPL Table Mountain Observatory 0.6-m telescope (TMO), collecting CCD spectra, BVRI colors and R-band lightcurves of essentially all radar targets observable from the northern hemisphere. Radar observations benefit greatly from optical observations, especially rotational lightcurves and taxonomic classification. We also seek to characterize Potentially Hazardous Asteroids (PHA: MOID ≤ 0.05 AU, H ≤ 22.0 mag) and low-ΔV (LDV: ΔV ≤ 6.29 km/s) near-Earth asteroids as they become available from our latitude. Between January 2009 and July 2010 we acquired data on 38 objects over 107 nights at TMO and 28 objects over 8 nights at P200. We will report our spectra, colors, and light-curve photometry for the following minor planets, with the taxonomic classification (Bus Taxonomy) derived from our data listed in parenthesis: 1991 AQ10 (Sq), 1991 DB (C), 1994 CC (Sq), 1996 EN (V), 1996 FG3 (C), 1998 CS1 (Sa), 1998 FW4 (Xc), 1998 OR2 (Xk), 1999 AP10 (Sa), 1999 AQ10 (S), 1999 LF6 (L), 1999 MN (Sq), 2000 TO64 (S), 2000 UJ1 (S), 2000 XK44 (S), 2001 CV26 (S), 2001 FE90 (A), 2001 FM129 (Sq), 2002 VY95 (C), 2003 EF54 (V), 2003 QO104 (S), 2003 YT1 (R), 2004 FG11 (V), 2005 CW25 (T), 2005 EK70 (Sq), 2005 YU55 (C), 2006 AS2 (C), 2007 MK13 (C), 2008 EE5 (Sl), 2008 EV5 (C), 2008 SV11 (CX), 2009 KC3 (CX), 2009 KD5 (L), 2009 OG (S), 2009 UD2 (S), 2009 UN3 (S), 2009 UV18 (Ld), 2010 GU21 (X), 3554 Amun (X), 4486 Mithra (S).
The Near-Earth Asteroid (NEA) 4055 Magellan was discovered by Glo Helin at Palomar Mountain (IAUC... more The Near-Earth Asteroid (NEA) 4055 Magellan was discovered by Glo Helin at Palomar Mountain (IAUC 4638) and was one of the first known minor planets with surface reflectance properties comparable to that of 4 Vesta (Tholen, 1988). Broad-band photometry and near-IR spectroscopy revealed strong 0.9 and 1.9 micron proxene bands, suggesting a compositional similarity of 4055 Magellan with that of 4 Vesta and the basaltic achondrite meteorites (Cruikshank et al. 1991). In anticipation of the Dawn mission to 4 Vesta we obtained 5 partial nights, 2010 August 9/10/12/13/14, of Bessel R photometry of 4055 Magellan at the Jet Propulsion Laboratory Table Mountain 0.6-m telescope (TMO). We measured a synodic period of 7.488+/-0.001 hr, similar to the 7.475+-0.001 hr period obtained by Pravec et al. (http://www.asu.cas.cz/ ppravec/newres.txt). Our object exhibited a large lightcurve amplitude (delta_M 0.8 mag) implying a highly elongated shape. We used our TMO photometry and the absolute magnitude as tabulated by the Minor Planet Center to construct a rudimentary solar phase curve. We derived a phase parameter g=0.30, similar to the phase behavior as measured by Pravec and colleagues (http://www.asu.cas.cz/ ppravec/neo.html). Our high g implies a shallow solar phase slope, consistent with the object's high albeldo (rho=0.31) obtained from thermal measurements (Delbo et al. 2003). The photometric properties of the V-type 4055 Magellan , such as shallow phase slope and high albedo, are consistent with 4 Vesta, giving us confidence in using NEA vestoids as photometric analogs for 4 Vesta.
The Near-Earth Object (NEO) 2002 VE68 was discovered by the LONEOS Survey on November 11, 2002 (M... more The Near-Earth Object (NEO) 2002 VE68 was discovered by the LONEOS Survey on November 11, 2002 (MPEC 2002-V52). With a semi-major axis of 0.723 AU, 2002 VE68 is in a 1:1 mean motion resonance with Venus and can be considered a quasi-satellite of the planet. Orbital integrations by Mikkola et al. (2004) suggest that 2002 VE68 was likely an NEO injected into its current orbit by a close Earth encounter approximately 7000 years ago and will remain a Venusian quasi-satellite for another 500 years. This object has been designated a Potentially Hazardous Asteroid by the Minor Planet Center. We took advantage of the object's 2010 apparition to collect rotationally resolved Bessel BVRI photometry over the course of three nights (November 10/12/13 2010) using the JPL Table Mountain 0.6-m telescope near Wrightwood, California. The object's mean colors (B-R=1.106+/-0.019 mag; V-R=0.419+/-0.021 mag; R-I=0.348+/-0.014 mag) are most compatible with an X-type spectral classification (Bus Taxonomy). A slight reflectance dip at 0.55 micron is consistent with the deep 0.50 micron feature observed in the spectrum of the E-type asteroid 2867 Steins (Weissman et al. 2008). The spectral resolution that our BVRI photometry affords is often insufficient to resolve the E-M-P sub-classes within the X-spectral complex (Tholen Taxonomy; Zelner et al. 1985). After converting the photometry from magnitude to flux units, we found a best-fit synodic period P_syn = 13.50+/-0.01 hr. Our photometry yields an absolute magnitude H_v=20.59+/-0.02 mag, implying an effective diameter D 200m (rho=0.25). The lightcurve amplitude of 2002 VE68 ( 0.9 mag) suggests that it may be a contact binary.
2009 KD5 was discovered May 26 2009 by the Observatorio Astronomico de Mallorca LSSS (La Sagra Sk... more 2009 KD5 was discovered May 26 2009 by the Observatorio Astronomico de Mallorca LSSS (La Sagra Sky Survey) Near-Earth Object (NEO) survey (MPEC 2009-K55) and identified as a Potentially Hazardous Asteroid (PHA) by the Minor Planet Center. The object's 2010 closest approach to the Earth is quite distant (delta=0.24 AU on June 29 2010). However, the apparition allows the NEO to be observed under slowly varying illumination and viewing geometry.
2009 KD5 was discovered May 26 2009 by the Observatorio Astronomico de Mallorca LSSS (La Sagra Sk... more 2009 KD5 was discovered May 26 2009 by the Observatorio Astronomico de Mallorca LSSS (La Sagra Sky Survey) Near-Earth Object (NEO) survey (MPEC 2009-K55) and identified as a Potentially Hazardous Asteroid (PHA) by the Minor Planet Center. The object's 2010 closest approach to the Earth was quite distant (delta=0.24 AU on June 29 2010). However, the 2010 apparition allows the NEO to be observed under slowly varying illumination and viewing geometry. We have analyzed six nights of Bessel BVRI observations at the JPL Table Mountain Observatory (TMO) 0.6-m telescope (6/15, 6/16, 6/19, 6/20, 7/03, 7/04 UT). The PHA's averaged broad-band colors (B-R=1.300+/-0.034 mag; V-R=0.491+/-0.027 mag; R-I=0.409+/-0.027 mag) were found to be most compatible with an L-type spectral classification (Bus & Binzel 2002). L-types asteroids are members of the S-family of asteroids and may represent surfaces highly processed by collisional gardening and space weathering. A solar phase curve constructed from our data was consistent with an assumed solar phase parameter g=0.15, yielding an Absolute Magnitude HV = 18.39 mag. Systematic departures in the night-to-night rotationally phase photometry suggested that the NEO is a binary asteroid. We have fit a two-period model for the lightcurve of 2009 KD5, with the primary P1 = 2.52 hr (very near the rotational break-up speed of a self-gravitating rubble pile) and secondary, presumably tidally-locked, component P2 = 21.7 hr. We have an additional two nights of unreduced photometry that should further constrain the asteroid's solar phase and rotational properties.
The near-Earth asteroid 66146 (1998 TU3) was discovered on 1998 October 13 by the LINEAR NEO surv... more The near-Earth asteroid 66146 (1998 TU3) was discovered on 1998 October 13 by the LINEAR NEO survey (MPEC 1998-U03). We obtained five nights of Bessel BVRI observations (2010 Aug 6,7,10,12,13 UT) and one night of Bessel R (August 8 PST) at the JPL Table Mountain Observatory (TMO) 0.6-m telescope near Wrightwood, California. These observations were obtained as part of our ongoing survey at TMO of Potentially Hazardous Asteroids (PHAs), planetary radar targets, and low delta-V near-Earth asteroids (NEOs). The object's rotationally averaged colors (B-R=1.238+/-0.011 mag; V-R=0.440+/-0.008 mag; R-I=0.275+/-0.010 mag) were found most compatible with an Sk-type spectral classification (Bus Taxonomy)/S-type (Tholen Taxonomy). This association was obtained through a comparison of our colors with the 1341 asteroid spectra in the SMASS II database (Bus & Binzel 2002). Our classification differs significantly from the Q-type taxonomy reported by Whitely (2002). Assuming a solar phase parameter g=0.15 we performed a period search using standard Fourier techniques. We found a best-fit rotational period Psyn=2.378+/-0.001 hr, in excellent agreement with the 2.3779+/-0.0004 period determined by Richards et al. (2007). The dispersion in the phased single period lightcurve strongly suggests that 1998 TU3 is be a binary system, with variations in observed flux caused by an unresolved, tidally locked secondary companion. Fitting a 2-period model as described by Pravec et al. (2000), we found that our photometry agrees well with a binary model (P1=2.378+/-0.01 hr, P2=28.28+/-0.05 hr). We have three additional nights scheduled for this object at TMO (Oct 8, 9, 10 2010 UT), extending our solar phase coverage and allowing us to refine our rotational models. 1998 TU3 will experience an exceptional apparition in 2012. This object may be a good candidate for shape/pole modeling via lightcurve inversion, especially if photometry can be obtained from both northern and southern hemispheres. We welcome any potential collaborations.
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Papers by Karen Garcia