Named in honor of Steven J. Ostro, planetary scientist at the Jet Propulsion Laboratory of the California Institute of Technology. Ostro has specialized in radar studies of solar system objects, including the Galilean satellites. He is the leader in radar research on minor planets and has used his observations to deduce their surface roughness and radar reflectivity. He has also combined his radar data with optical rotational lightcurves to study the shapes and axial orientations of minor planets. (M 11749) _ _.