Positions of Uranus and Its Main Satellites

Abstract

We present astrometric positions of Uranus and its satellites Miranda, Ariel, Umbriel, Titania, and Oberon, determined in the International Celestial Reference System, from 1758 frames observed over 105 nights between 1982 and 1998. All the positions of the satellites were reduced using secondary frames referred to the Tycho-2 Catalogue from photographic plates and CCD frames obtained with the 1.6 m reflector at the Laboratório Nacional de Astrofísica in Brazil. The images of Uranus were overexposed and thus not were measured in the frames. Its positions were instead calculated from the satellites, with the exception of Miranda, using their differential positions as given by the ephemeris GUST86. The positions of the planet were compared with the planetary ephemeris DE403, and the residuals have a mean and standard deviation, respectively, of -0.09" and 0.14" for (O-C)_α and -0.01" and 0.15" for (O-C)_δ. The results are similar for the satellites.

Based on observations made at the Laboratório Nacional de Astrofísica, MCT, Itajubá, Brazil.