Ground-Based Photometry of Asteroid 951 Gaspra

Asteroid 951 Gaspra became the first minor planet visited by a spacecraft. We report here on extensive photometric observations of Gaspra during three apparitions prior to the Galileo flyby. Analysis of the solar phase angle dependence of the brightness gives a G value of approximately 0.29 for the lightcurve maxima. The amplitude phase dependence is also investigated. These observations complement the Galileo data and they are of high importance for our understanding of the lightcurve inversion problem in general. The data were input to groundbased modeling for prediction of the shape and spin vector of Gaspra. © 1993 by Academic Press, Inc.