We describe the Attitude Star Catalog produced for the Gaia mission. This catalog is being used by Gaia for the first on-ground attitude reconstruction. Originally it was simply a subset of the Initial Gaia Source List but this subset not meet the isolation requirements and it contained a significant number of double entries. As a result during the commissioning phrase of Gaia a new generation of this catalog that fulfills better the attitude reconstruction requirements was requested. Here we describe the Attitude Star Catalog production and properties.

The Attitude Star Catalog was made by combining 7 all sky catalogs and selecting ASC entries based on magnitude, isolation and astrometric precision criteria. The catalog has 8173331 entries with estimates of the positions at 2000, proper motions and magnitudes (Gaia \(G\), Gaia \(G_{rvs}\), red \(R_{F}\) & blue \(B_{J}\)). It is publically available from the CDS Strasbourg and the IGSL website.