The preliminary shape of Ceres

Kurzfassung

Methods have been developed to derive the global shape of an asteroid quickly with the help of limb images taken by spacecraft. Topographic profiles are found by applying a contrast-based search along the limb. By minimizing height differences at crossover locations between the individual limb profiles their locations are improved and a global network is created. We used images taken by the Dawn spacecraft during the Ceres approach in February of 2015 to derive the shape of the asteroid. 87 images from the RC1, RC2, OPNAV 4, OPNAV 6, and OPNAV 7 phases have been examined yielding a network of topographic profiles spanning from ca. 78°S to 83°N. By fitting a tri-axial ellipsoid to the data we found Ceres to be an oblate spheroid with axes significantly smaller than previously estimated.