Astrometric results of observations of mutual occultations and eclipses of the Galilean satellites of Jupiter in 2003

¹ Sternberg astronomical institute, 13 Universitetskij prospect, 119992 Moscow, Russia e-mail: emelia@sai.msu.ru
² Institut de mécanique céleste et de calcul des éphémérides – Observatoire de Paris, UMR 8028 du CNRS, 77 avenue Denfert-Rochereau, 75014 Paris, France

Received: 5 January 2006
Accepted: 2 March 2006

Abstract

Context. The photometry of mutual occultations and the eclipses of natural planetary satellites can be used to infer very accurate astrometric data. This can be achieved by analyzing the light curves of the satellites observed during these mutual events.

Aims. The final goal of observations is to refine the models of motion for the natural satellites, and to develop a very accurate photometric model of mutual occultations and eclipses of satellites. This paper is focusing on the differences of topocentric or heliocentric coordinates of satellites pairs by analyzing the photometry of mutual occultations and the eclipses of natural satellites.

Methods. We propose the most accurate photometric model of mutual events to date based on all available data about the satellites, and have developed the corresponding method for extracting astrometric data. We analyze the errors of astrometric results obtained in terms of different scattering laws allowing for reflecting properties of the satellites surfaces. In addition we consider how to allow various previously neglected effects.

Results. We describe the results obtained by applying our method to observations of mutual occultations and eclipses of the Galilean satellites of Jupiter made in 2002–2003. We show that the coordinate errors due to irreducible systematic errors of photometry are about the same as the errors introduced by neglecting the above effects. We find the available maps of satellites surfaces to be unsuitable for deriving photometric event models.