Photometry with a periodic grid

The Hipparcos satellite successfully gathered astrometric and photometric information for a few solar system objects including natural satellites. In contrast to the case for asteroids, the Hipparcos main-mission does not provide the photometry – in the conventional sense – of planetary satellites. Nevertheless, valuable photometric results can be obtained, such as a modelling of the centre-to-limb darkening of the bodies. We present in this paper results obtained for the photometry with a periodic grid of the satellites J2 Europa and S6 Titan from the Hipparcos main mission and within the FAST data-reduction Consortium. The Minnaert parameter of S6 Titan is found to be , and for J2 Europa, . Brightness variations with orbital phase are also given for Europa.