In this paper we develop a differential astrometric framework that is appropriate for scanning space satellite such as Gaia. We apply it to the first of GAREQ fields, which fruit dedicated efforts within Gaia project focused on measuring relativistic deflection light close Jupiter's limb. This provides preliminary assessment of: a) observability Jupiter, and, b) Gaia's capabilities under extrem...

The analysis of planetary satellites or asteroids ground based observations is quite similar. Our first goal was to improve the astrometric reduction for digitized photographic plates in case of too few reference stars and to propose solutions. We here present astrometric techniques used for old observations of the Galilean satellites made with the 26-inch refractor of USNO in Washington DC fro...