INITIAL REFINEMENT OF MINOR PLANET ORBITS FOR POINTING AND OBSERVATION WITH THE HUBBLE SPACE TELESCOPE

Refinements of the orbital elements for 24 minor planets that will be observed with the Fine Guidance Sensors (FGSs) on the Hubble Space Telescope are presented. The accuracy of these orbits is discussed in the context of the ephemeris requirements for target acquisition with the FGSs. Comparisons with standard catalog orbits are made to evaluate the suitability of the use of the catalog orbits for HST pointing. We find that the orbits published in the most recent Minor Planet Circulars are capable of positional predictions that are accurate at the 1 arcsec level. However, there are still many orbits that have not been revised in the last 10 yr and these should not be used for critical pointing ephemerides. In many cases the orbital elements will have to be refined using recent ground-based observations before a minor planet can be reliably observed by HST.