Updated ephemeris of Phoebe, ninth satellite of Saturn

Abstract

Context. The theoretical model of natural satellite motion may need improvement each time new observations of a considerable amount are accumulated over a significant time interval. Aims. The goal of our work is to elaborate the ephemeris of Phoebe based on all ground-based observations available to date and readily accessible for any user via the Internet. Methods. Our model for the orbit of Phoebe is based on numerical integration of the equations of motion. In the theory of satellite motion, all necessary perturbations were taken into account. To produce the ephemeris of Phoebe, we used a database that contains all published ground-based observations and expands constantly as new observations appear. Results. The new ephemeris of Phoebe, based on 1606 ground-based observations made at 39 observatories in the 103 year time interval, was elaborated. The real precision of the ephemeris is limited by the observational precision and is not worse than 0.15 �� . The ephemeris is available at: http://www.imcce.fr/sat and http://www.sai.msu.ru/neb/nss/index.htm. The ephemeris of Phoebe will be updated as new observations become available.