Ida lightcurves: Consistency with Galileo shape and photometric models

Abstract

Models for the shape and global photometric behavior of 243 Ida derived from Galileo images have been used to model the asteroid's telescopic lightcurves. We find excellent agreement between the calculated and observed times of lightcurve extrema, confirming the sidereal rotation period of 4.633632 ± 0.000007 hr determined by Binzel et al. (1993. Icarus 105, 310-325.). The shapes and amplitudes of the synthetic and observed lightcurves agree with each other to within ≈0.05 mag, and the average offset in absolute photometry between model and observation is only 0.01 mag. This consistency confirms the accuracy of the shape model derived for Ida by Thomas et al. (1996. Icarus 120, 20-32.) and supports the model of the asteroid's photometric behavior developed by Helfenstein et al. (1996. Icarus 120, 48-65.). © 1996 Academic Press, Inc.