Accuracy of calibrated data from the SDSS moving object catalog, absolute magnitudes, and probable lightcurves for several asteroids

¹ Dept. of Astronomy, Physics of the Earth, and Meteorology, FMFI, Comenius University, 84248 Bratislava, Slovakia
² Astronomical Institute, AS CR, 25165 Ondřejov, Czech Republic e-mail: galad@fmph.uniba.sk

Received: 8 January 2010
Accepted: 8 February 2010

Abstract

It would seem that the calibrated observations obtained by the Sloan Digital Sky Survey (SDSS) by themselves would be, at best, marginally useful for the secure determination of asteroid rotation lightcurves, mostly due to the scarcity of data for a particular object in a given apparition as well as because of the sometimes low photometric quality of the SDSS data. Despite these shortcomings, it was decided to see if the SDSS data could be used to help find the lightcurve parameters of at least some asteroids. Observations of ten asteroids obtained by the SDSS are compared here with lightcurves obtained by asteroid photometric stations using dense data sets. Three asteroids observed during the same apparition as the SDSS observations served to determine the accuracy of the SDSS data. Except for occasional outliers identified on the basis of deviating color indices, the accuracy of the observations was found to be about 0.03 mag in the V band on average, which is a generally accepted level of quality for most asteroid photometry.
In addition to the ten asteroids with known lightcurves, another 54 asteroids without known lightcurves, but with more than 20 observations by SDSS, were also examined to derive their absolute magnitudes (H) and plausible composite lightcurves. Lightcurve analyses of (12104) Chesley, (32257) 2000 OW₅₂, (39132) 2000 WU₅₈, (156751) 2002 XL₉₂, (219686) 2001 WE₃₇, 1992 WW₆, and 2007 EP₃₉ are presented. The asteroids studied in this paper were found to be mostly fainter than predicted from the H values given by the Minor Planet Center in its Orbit Database. The difference between the H values slightly correlates with the lightcurve amplitude.