A date for which star coordinates and other data are calculated in star catalogues; also known as a fundamental epoch. The standard place of a star is its right ascension and declination referred to the mean equator and equinox of the chosen epoch. By referring all star positions to a standard date, the effects of proper motion, precession, and nutation are removed. The standard epoch currently used is the Julian epoch J2000.0, which corresponds to the date 2000 January 1.5 TDB.
Subjects: Astronomy and Astrophysics.