Robert, V. ; De Cuyper, J. ; Arlot, J. ; Lainey, V. ; Pascu, D.

published in Bulletin of the American Astronomical Society, 42, pp. 9.17 (2010)

Abstract: A new astrometric reduction of old photographic plates that benefits from modern technologies can provide a better knowledge of the orbital motion of planetary satellites. In that respect, an international collaboration has been set up between the USNO, the OBSPM and the ROB to digitize USNO plates with the new generation scanning machine. The procedure can be applied to various photographic plates and it is assumed that the astrometric results will be the most precise. Here we consider a set of a few hundred photographic plates of the Galilean satellites, taken at the USNO, and covering the years 1967-1998. A specific procedure was developed to obtain a high accuracy in the position of each moon. So far, 30 plates were digitized at the Paris Observatory with the MAMA machine (2006 and 2007) and the complete series is now being digitized at the Brussels Observatory with the new DAMIAN machine. The first results suggest an accuracy better than 50 mas in (RA,Dec) positions of each moon. Since the position of Jupiter may also be deduced from the observed Ra and Dec positions of the satellites, using the Galilean satellite ephemerides, we can also assess the accuracy of Jupiter's ephemeris. First astrometric results will be presented.

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