We present results from multi-wavelength observations of outer-belt asteroid 279 Thule and comet C12002 CE10 (LINEAR). The orbital elements of the second object, formerly classified as asteroid 2002 CE10, at first led to its identification with a group of asteroids called the Damocloids. The Damocloids' orbits are similar to Halley family comets (HFCs), and there is suspicion that the Damocloids are inactive HFC nuclei. Following observations by the 8.2 m Japanese Subaru telescope in August 2003, which determined that 2002 CE IO had a characteristic tail (Takato et al; 2003), it was re-classified as comet C/2002 CE10 (LINEAR).
We observed these and other objects with filters close to the Johnson-Kron-Cousins BVRl filters corresponding to the blue, visible, red, and near-IR wavelengths using the 0.9m SMARTS telescope at Cerro-Tololo Inter-American Observatory during October 2003. Using the image reduction routines (imred) of the Image Reduction and Analysis Facility (NOAO Xl IIIRAF), we removed the bias caused by dark currents, and flat fielded the data to improve the signal-to-noise ratio (SNR).
Instrumental magnitudes for all objects were extracted using the aperture photometry package (apphot). Landolt standard stars were used to solve the transformation equations and extract extinction coefficients. Photometric calibration routines (photcaI) allowed us to use the extinction coefficients and instrumental magnitudes to determine magnitudes in the Landolt standard system. We computed absolute magnitudes for 279 Thule and C/2002 CE10 (LINEAR) in the VR bands by correcting for the changing geocentric distance, heliocentric distance, and solar phase of the object. 279 Thule was found to have a mean absolute visual magnitude of 8.66±0.OJ and a V-R color of 0.44±0.03, when corrected for solar phase using the standard IAU phase relation (Bowell et al; J989). We discuss the suitability of the standard phase relation for 279 Thule. We place constraints on the size of the objects. We determine the rotation period for 279 Thule to be 7.6±0.5 hrs, using an implementation of the phase dispersion minimization (PDM) algorithm first developed by Stellingwerf (1978). It is likely that observations of C12002 CE lU (LINEAR) have been contaminated by near nucleus coma.
Narayan '05, Gautham S., "Photometry of Outer-belt Objects" (2005). Honors Projects. Paper 3.