The ACT Reference Catalog

The U.S. Naval Observatory compiled the ACT Reference Catalog, containing 988,758 stars covering the entire sky, to provide accurate proper motions for the majority of the stars in the Tycho Catalogue (ESA SP-1200). Positions from new reductions of the Astrographic Catalogue (AC 2000) were combined with those of Tycho, and the large epoch span between the two catalogs was used to obtain proper motions about an order of magnitude more accurate than those published in the Tycho Catalogue.

The ACT Reference Catalog includes positions, proper motions and error estimates on the Hipparcos System (J2000.0) for epoch J2000.0. Photometric data (B and V) from Tycho are included, as well as cross references to the Tycho, AC 2000, Bonner Durchmusterung (BD), Cordoba Durchmusterung (CD), Cape Durchmusterung (CpD), Henry Draper (HD) and Hipparcos Catalogues.

To enable rapid access of specific stars in the catalog, WCSTools software numbers each star using its RA region number (0000-2330) and a five-digit star number within each region, separated by a decimal point. sact lists ACT stars by number or sky region. imact lists the ACT stars within an IRAF or FITS image with a world coordinate system defined in its header.

ACT Format

ACT at USNO

[WCSTools sact] [WCSTools imact]