ASTROMETRY BY GROUND-BASED TELESCOPES FOR THE GAIA MISSION

The space astrometry Gaia mission is operating since July 2014 (Gaia Collaboration; Brown, A. et al., 2016; Gaia Collaboration; Prusti, T. et al., 2016). As planned, Gaia detects many moving objects in its fields of view during its scanning process of the sky. Several months were necessary to tune the different parameters for filtering these objects among a huge number of sources in the Gaia focal plane. But since October 2016, a short term processing is operating for triggering alerts when unknown Solar System Objects are detected by the space probe. In this context, ground-based telescopes are an important support for the Gaia mission. We describe here the alert system developed and give an overview of the first results.