EDP Sciences
Free access
Volume 422, Number 1, July IV 2004
Page(s) 377 - 379
Section Celestial mechanics and astrometry
DOI http://dx.doi.org/10.1051/0004-6361:20035706

A&A 422, 377-379 (2004)
DOI: 10.1051/0004-6361:20035706

1997-2000 CCD astrometric observations of Saturn's satellites and comparison with theories

R. C. Qiao1, 2, K. X. Shen1, 2, D. Harper3 and J. R. Liu1, 2

1  National Time Service Center, The Chinese Academy of Science, PO Box 18, Lintong, Shaanxi 710600, PR China
2  United Laboratory for Optical Astrometry, The Chinese Academy of Science, PR China
3  Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SA, UK

(Received 18 November 2003 / Accepted 16 April 2004 )

As a continuation of the observing campaign 1994-1996 (Qiao et al. 1999), this paper presents 1167 new measurements of the positions of the major Saturnian satellites obtained using a CCD camera on the 1.56 m reflector at the Sheshan station near Shanghai during the period 1997-2000. The observations include the major satellites exclusive of the faintest satellite, Hyperion. The analytical theory TASS was chosen for astrometric calibration of the CCD and theory computation. Analysis of the data as inter-satellite positions shows that the observations of Tethys, Dione, Rhea, and Iapetus have a standard deviation about the mean of  $0\farcs06$, which matches the accuracy of our earlier observations. However, for a few of the inner satellites, including Mimas, Enceladus, we have obtained poorer residuals up to  $0\farcs1$ to  $0\farcs2$ which we ascribe to lower quantum efficiency of the CCD.

Key words: planets and satellites: individual: saturn -- astrometry

Offprint request: R. C. Qiao, rcqiao@ntsc.ac.cn

Tables at the CDS

© ESO 2004