The U.S. Naval Observatory has completed the compilation of the ACT Reference Catalog, containing 988,758 stars covering the entire sky. The motivation behind the ACT was to provide accurate proper motions for the majority of the stars in the Tycho Catalogue (ESA SP-1200). To do this, positions from new reductions of the Astrographic Catalogue (AC 2000) were combined with those of Tycho. The large epoch span between the two catalogs yields proper motions about an order of magnitude more accurate than those published in the Tycho Catalogue. The astrometric data contained in the ACT Reference Catalog include positions, proper motions and error estimates. These are on the Hipparcos System (J2000.0) for epoch J2000.0. Photometric data (B and V) from Tycho are included. Additionally, cross references to the Tycho, AC 2000, Bonner Durchmusterung (BD), Cordoba Durchmusterung (CD), Cape Durchmusterung (CPD), Henry Draper (HD) and Hipparcos Catalogues are given.
The Tycho Reference Catalogue (TRC) contains high-quality positions and proper motions for 990182 stars of the Tycho Catalogue. The proper motions were derived from Tycho positions and Astrographic Catalogue positions reduced to the Hipparcos system. The median accuracy of the TRC position components is 40 mas at J1991.25. The median accuracy of the proper motion is about 2.5 mas/yr. Systematic errors are less than about 1.0 mas(/yr). The quality of the proper motions in TRC is assessed by comparison with the Hipparcos and Tycho Catalogues. Comparison with the recent ACT Catalogue which is based on an independent reduction of the same observations as used for constructing the TRC is reported.
