The orbit of Nereid based on observations

Abstract

Ephemerides of natural satellites are needed to carry out space missions to planets and to study the dynamics of Solar system bodies. Continuous observations of planetary satellites allow new, more accurate ephemerides to be derived. In this paper a new model of the motion of the Neptunian satellite Nereid is developed. The model is based on all published (736) and unpublished (140) ground-based observations and 72 observations made by the Voyager spacecraft in 1989. The root-mean-square (rms) deviations of the observed satellite coordinates from their theoretical values are equal to 0.30 and 0.32arcsec in right ascension and declination, respectively. The main contributors to these deviations are early ground-based observations of Nereid. Estimations of the precision of the ephemeris of Nereid made by our original method show that the errors of the ephemeris do not exceed 0.03arcsec (1σ) up to 2020. Comparing our ephemeris of Nereid with the Jet Propulsion Laboratory (JPL) results, the discrepancies do not exceed 0.04arcsec in right ascension and declination over the 1980-2011 time period. A new ephemeris of Nereid is proposed via the MULTI-SAT ephemeris facility. © 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS.