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.

Reference Papers:
The catalogue is described in "The Tycho-2 Catalogue of the 2.5 million brightest stars", E. Høg, 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. Høg, C. Fabricius, V.V. Makarov, et al., A&A, 357, 367-386 (2000).

Catalogue Access:
The data is available in the Hipparcos and Tycho Legacy Archive via the ESASky Legacy Table Access Protocol (TAP) service (in the Topcat tool, select the option "Table Access Protocol (TAP) Query" in the VO menu and paste the TAP url http://esaskylegacy.esac.esa.int/esasky-legacy-sl-tap/tap in the "Select Service” pane). The data is also available from CDS in VizieR, from ESASky, and from the Gaia Archive.

Related links:
Some further information is available here.