Positional measuring procedure and CCD observations for Saturnian satellites^*

¹ Department of Computer Science, Jinan University, Guangzhou 510632, PR China and United Laboratory for Optical Astronomy, Chinese Academy of Sciences
² Institut de mécanique céleste et de calcul des éphémérides, Observatoire de Paris, UMR 8028 du CNRS and Université de Lille, 59000 Lille, France
³ Shanxi Astronomical Observatory, Chinese Academy of Sciences, Lintong, Shanxi 710600, PR China and Chinese National Astronomical Research Center

Corresponding author: Q. Y. Peng, pengqy@public.guangzhou.gd.cn

Received: 25 July 2001
Accepted: 13 September 2001

Abstract

A positional measuring procedure for the eight major satellites of Saturn (Mimas, Enceladus, Tethys, Dione, Rhea, Titan, Hyperion and Iapetus) is developed. Using this procedure, 199 frames of CCD images, obtained with the 1-meter telescope at the Yunnan Observatory from 1996–2000, are measured. These positions are compared to the ones computed with the Vienne & Duriez ephemerides (TASS1.7). The calibrated parameters of the CCD scale and orientation are determined by the comparison of their measurement coordinates with computed positions of four bright satellites: Tethys, Dione, Rhea and Titan. A catalog of 913 differential positions has been obtained. Analysis of the data as inter-satellite positions shows that these observations of the above-mentioned four satellites have root-mean-square residuals of 0.04 arcsec in the sense of (O–C) (Observed minus Computed). The positional measuring procedure is shown to be good enough to obtain a small dispersion in the observations for the major Saturnian satellites.