Ceres: High-resolution imaging with HST and the determination of physical properties
Russell, C. T.; Stern, S. A.; Young, E. F.; McFadden, L. A.; Thomas, P. C.; Sykes, M. V.; Parker, J. W.
United States
Abstract
Nine HST orbits have been used to image Ceres using the High Resolution Camera of the Advanced Camera for Surveys. Two hundred and fifty-nine images in three filters (F555W, F330W and F220W) were obtained covering the entire surface. Two visible features are readily apparent, a dark patch and a bright point. The bright spot was suitable for control point work enabling the spin axis (291° RA and 59° Dec.) and the latitude (14°N) of the bright point to be determined. Limb accuracies of approaching 0.1 pixel accuracy enabled the shape of Ceres to be determined to be rotationally symmetric with a short axis of 909 km and a long axis of 975 km. Analysis of these images is preliminary and continues to be refined.