CCD POSITIONS FOR THE OUTER PLANETS IN 1996-1997 DETERMINED IN THE EXTRAGALACTIC REFERENCE FRAME

This paper presents 316 new equatorial positions for the planets Uranu s, Neptune, and Pluto obtained in 1996-1997 with the Flagstaff Astrome tric Scanning Transit Telescope (FASTT). All the positions were determ ined in the extragalactic reference frame using CCD observations and a re accurate to similar to +/-0.'' 2 in each coordinate. When these pos itions are compared with the latest JPL ephemerides (DE405), there is generally good agreement between the observed and calculated positions for these planets. In particular, the offset in the declination of Pl uto (Delta delta similar to 0.'' 1) is no longer evident, and conseque ntly, the DE405 is obviously an improvement over its predecessor, the DE403, in that respect. There appears to be a small offset, similar to 0.'' 09, however, in the right ascensions of Uranus, which might be a ccidental or caused by errors in the FASTT observed or DE405 calculate d ephemeris positions; future observations are planned to clarify this issue. With the release of the Hipparcos Tycho, and ACT catalogs of e xtremely accurate reference star positions, it is now possible for tel escopes, such as the FASTT, to determine the positions of planets and their satellites directly in the international celestial reference fra me (ICRF) with greatly improved accuracy (similar to +/-0.'' 06) in ea ch coordinate. All future FASTT observations will be made in this mann er, and the FASTT observing program will be expanded to include satell ites of planets as well.