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Astron. Astrophys. 357, 367-386 (2000)

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Construction and verification of the Tycho-2 Catalogue *

E. Hog 1, C. Fabricius 1, V.V. Makarov 1, U. Bastian 2, P. Schwekendiek 2, A. Wicenec 3, S. Urban 4, T. Corbin 4 and G. Wycoff 4

1 Copenhagen University Observatory, Juliane Maries Vej 30, 2100 Copenhagen O, Denmark
2 Astronomisches Rechen-Institut, Mönchhofstrasse 12-14, 69120 Heidelberg, Germany
3 European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching, Germany
4 United States Naval Observatory, 3450 Massachusetts Ave N.W., Washington D.C. 20392-5420, USA

Received 28 December 1999 / Accepted 7 March 2000


The construction of the Tycho-2 Catalogue is described. The catalogue contains astrometric positions and proper motions as well as two-colour photometric data for 2.5 million stars. The Tycho-2 positions and magnitudes are based on precisely the same observations as the original Tycho Catalogue (hereafter Tycho-1) collected by the sky mapper of the ESA Hipparcos satellite, but Tycho-2 is much bigger and slightly more precise, owing to a more advanced reduction technique. Components of double stars with separations down to 0.8 arcsec are included. Proper motions precise to about 2.5 mas/yr are given as derived from a comparison with the Astrographic Catalogue and 143 other astrometric catalogues, all reduced to the Hipparcos celestial coordinate system. Tycho-2 supersedes in most applications Tycho-1, and the ACT and TRC catalogues based on Tycho-1.

Key words: astrometry – techniques: photometric – catalogs – methods: data analysis

* Based on observations made with the ESA Hipparcos astrometry satellite.

Send offprint requests to: E. Hog (erik@astro.ku.dk)

© European Southern Observatory (ESO) 2000

Online publication: May 3, 2000