Positions for the outer planets and many of their satellites. IV. FASTT observations taken in 1999-2000

This paper presents 1201 new equatorial positions taken in 1999-2000 for th e outer planets Uranus, Neptune, and Pluto, as well as for 17 satellites of Jupiter-Neptune. Additional positions for Jupiter, Saturn, Uranus, and Nep tune can be derived from the planetocentric orbits of their satellites give n in this paper. All the positions were determined in the International Cel estial Reference Frame (ICRF) from CCD observations taken with the Flagstaf f Astrometric Scanning Transit Telescope (FASTT) using differential reducti ons. Accuracies of +/-0." 08 to +/-0." 28 were achieved, depending on the s ignal-to-noise ratio observed for each object. When new and older FASTT pos itions are compared with modern Jet Propulsion Laboratory (JPL) ephemerides , there is usually good agreement (+/-0." 1 and often much better) between theory and observation. In particular, the agreement with DE405 for the pla nets Jupiter-Pluto is always better than +/-0 ".05, when results are averag ed over several years. Exceptions include the outer satellites of Jupiter ( Elara and Pasiphae) and two satellites of Uranus (Titania and Oberon), whos e ephemerides probably need improvement.