An automated system for predicting occultations of stars by planets and satellites has been developed based on rapid star catalog access, JPL planetary ephemerides, and additional satellite orbit computations. The Space Telescope Guide Star project has developed an all-sky catalog covering sources almost as faint as previous photographic occultation plate searches have gone. A search was undertaken using the Space Telescope Guide Star catalog for occultations by Uranus, Neptune, and Pluto from 1989 to 1999. In addition to finding possible occultations, a comparison of Guide Star Catalog positions with astrometric plate positions for stars from V=9 to V=15 was made.