The Tycho-2 Catalogue
The Tycho-2 Catalogue is an astrometric reference catalogue containing positions, proper motions and two-colour photometry for the 2.5 million brightest stars in the sky. The catalogue is based on observations made using the Hipparcos satellite star mapper and is constructed using the same observations that were used to create the original Tycho catalogue. Improved reduction techniques have resulted in a catalogue with significantly more entries and in improved precision.
The catalogue is described in "The Tycho-2 Catalogue of the 2.5 million brightest stars", E. Hog, C. Fabricius, V.V. Makarov, et al., A&A, 355, L27-L31, (2000).
Details of the data reduction, catalogue construction and verification of the results can be found in "Construction and verification of the Tycho-2 Catalogue", E. Hog, C. Fabricius, V.V. Makarov et al., A&A, 357, 367-386 (2000)
The Tycho-2 catalogue was distributed on CD-ROM. They can no longer be ordered from ESA since the printed volumes have been sold out, but they are available in many scientific libraries, e.g. the Strasbourg Data Centre.
An example link to the catalogue from CDS in VizieR: catalogue I/259. To download the data, click on the Tar or FTP tab in VizieR.
Tycho-2 is included in the Multiparameter Search Tool on this site.
Some further information is also available here.