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gaia data release 3 documentation

15.3 External catalogues matched with Gaia DR3

15.3.6 Hipparcos-2

Reference papers:
van Leeuwen 2007a;
van Leeuwen 2007b.

A new reduction of the astrometric data as produced by the Hipparcos mission has been published, claiming accuracies for nearly all stars brighter than magnitude Hp = 8 to be better, by up to a factor 4, than in the original catalogue. The formal errors on the parallaxes for the new catalogue are confirmed. The presence of a small amount of additional noise, though unlikely, cannot be ruled out. The new reduction of the Hipparcos astrometric data provides an improvement by a factor 2.2 in the total weight compared to the catalogue published in 1997, and provides much improved data for a wide range of studies on stellar luminosities and local galactic kinematics.
Hipparcos-2 contains 117 955 sources.

Cross-match algorithm

According to the definition used in this work, Hipparcos-2 is a sparse catalogue. In the cross-match algorithm Hipparcos-2 is thus the leading catalogue, this means that counterparts for Hipparcos-2 objects are searched for in Gaia. For this catalogue the special treatment to account for the small issues in Gaia astrometry, especially for bright stars, was applied.