This table is a subset of GaiaSource 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. All rows have Gaia solution id
1635378410781933568.