A&A 389, 325-333 (2002)
Astrometry from CCD photometry of mutual events of Jovian satellites from VBO during 1997R. Vasundhara
Indian Institute of Astrophysics, Bangalore 560034, India
(Received 12 February 2002 / Accepted 5 April 2002 )
Astrometric results of CCD observations of the mutual events of the Galilean satellites of Jupiter from the Vainu Bappu Observatory are presented. The shifts in the photo-centers on the disks of Io and Europa due to albedo variations inferred from the available mosaics of Galileo imagery are determined. The estimated shifts from 90 km East to 50 km West on Io and from 50 km East to 30 km West for Europa during one orbital period are comparable to the accuracies provided by the present-day ephemerides. In a given mutual event series, the mutual events involving a given satellite pair dominate in number and occur nearly at the same orbital longitude within ; all the events are therefore delayed or all of them advanced depending on the direction of the shift of the photo-center. The implications of including these cumulative and sustained longitude residuals on the constructed ephemerides are discussed.
Key words: eclipses -- astrometry -- ephemerides -- occultations -- planets and satellites: general
© ESO 2002