Note: Errors found in the Hipparcos catalogue are reported in the file errata.htx
Note: Note that the errors on the proper motions are large (∼50mas/yr), and therefore the positions computed at an epoch different from 1991.25 have a large (∼0.4") uncertainty. The Tycho Epoch Photometry data can be accessed from the morePhoto column (includes VT, BT and Hp photometric data for Hipparcos stars [filter responses]
Note: The Naval Observatory Merged Astrometric Dataset (NOMAD) contains astrometric and photometric data for over 1 billion stars derived from the Hipparcos (I/239), Tycho-2 (I/259), UCAC2 (I/289), and USNO-B1.0 (I/284) catalogs for astrometry and optical photometry, supplemented by 2MASS (II/246) near-infrared photometry. An efficient remote query program findnomad1 is available in the cdsclient package, for Unix/Linux platforms