The lightcurve inversion method is a powerful tool for deriving asteroid physical models (spin states and shapes) from their disk-integrated photometry. A typical input data set for a main belt asteroid consists of tens of lightcurves from at least three apparitions. As has been shown by Kaasalainen (2004, A&A 422, L39), it is also possible to use calibrated photometry sparse in time. This approach has been tested on synthetic data sets with accuracy and cadence expected for the Pan-STARRS project (Durech et al. 2006, EM&P 97, 179). At present, new accurate photometric data are not yet available. However, it is possible to combine sparse photometry obtained during astrometric observations with a few dense lightcurves and in some cases derive new asteroid models from such combined data sets.We present about twenty new asteroid models derived from combined data sets. Dense lightcurves (the majority of them from the Uppsala Asteroid Photometric Catalogue) were combined with sparse photometric data from astrometric observations carried out at the US Naval Observatory in Flagstaff. The accuracy of the sparse photometry is about 0.08-0.1 mag, which is in some cases enough to derive a unique model. We have performed many tests that confirm credibility of our results and show typical uncertainties in the shape/pole/period determination. Although the shape models are coarse and may change with new data, the error in the pole direction is usually not higher than 20 deg of arc. In some cases, when the pole direction is not unique, the only physical parameters that can be determined are the rotation period and the ecliptic latitude of the spin axis.
AAS/Division for Planetary Sciences Meeting Abstracts #39
- Pub Date:
- October 2007