Catalogues of Fundamental Stars

The Catalogues of Fundamental Stars are six catalogs (plus some supplements) of astrometric data, numbered one through six and dating from 1897 to 2000. Each covers selected stars, on the order of a thousand. The aim has been to establish a celestial reference frame for use with celestial coordinate systems. The reference frame is defined through measured angular distances between these stars, determined as carefully as possible, and the coordinate system is tied to it by defining its origin and axes through such angular distances. The 1963 catalog (FK4) was commonly used with B1950 equatorial coordinate system, and the 1988 catalog (FK5) with J2000.

More recent celestial reference frames are based on satellite astrometry, such as HCRF and Gaia-CRF3, and those based on quasars, such as the ICRF, used by the International Celestial Reference System (ICRS).