Tycho-Gaia Astrometric Solution (TGAS) Source Table

This table is a subset of gaia_source comprising those stars in the Hipparcos and Tycho-2 Catalogues for which a full 5-parameter astrometric solution has been possible in Gaia Data Release 1. This is possible because the early Hipparcos epoch positions break some degeneracies due to the limited Gaia time coverage. This table contains a substantial fraction of the around 2.5 million stars in the Hipparcos and Tycho-2 catalogue. Many stars have been excluded due to several reasons, such as saturation, cross-match errors or bad astrometric solution. This dataset or service is made available by the Infrared Science Archive (IRSA) at IPAC, which is operated by the California Institute of Technology under contract with the National Aeronautics and Space Administration.