Results of Astrometric Observations of Distant Satellites of Jupiter with the New Telescope of the Caucasian Mountain Observatory, Sternberg Astronomical Institute, Moscow State University

Abstract

Replenishment of the database of observations of distant satellites of planets is always useful, since the accuracy of the motion models and ephemeris depends not only on the accuracy of observations. Accuracy improves with increasing observation time. Therefore, observations made even with the same accuracy are in demand. Astrometric observations of two distant satellites of Jupiter were carried out at the Caucasian Mountain Observatory (CMO) of the Sternberg State Astronomical Institute, Moscow State University, on a new telescope with a mirror diameter of 2.5 m in 2017. As a result, six positions of the J6 satellite (Himalia) and 27 positions of the J8 satellite (Pasiphae) are obtained. The root-mean-square deviations from the ephemeris for all 33 observations of these two satellites were 0.085″ in right ascension and 0.064″ in declination. This accuracy corresponds to the current level of ground-based observations. Our refinements of the orbits for the MULTI-SAT ephemeris server based on all available observations showed that the weighted root-mean-square values of the angular deviations of the measured positions from those calculated for satellites J6 (Himalia) and J8 (Pasiphae) are 0.22″ . At the same time, the accuracy of the ephemeris is estimated with the MULTI-SAT server for 2017 at 0.008″ for J6 (Himalia) and 0.05″ for J8 (Pasiphae). New observational data will be useful for refining the motion models of distant satellites of Jupiter.