Astrophysics (Index)About

J2000.0 equinox

(equinox as of the J2000.0 epoch used as a positional reference)

J2000.0 equinox is a standard direction (equivalently, a specific point on the celestial sphere) currently used as a reference in astronomy, being the position of the equinox as of epoch J2000.0. It is used as the basis for current standard equatorial coordinate system, i.e., right ascension and declination, right ascension counting up from the vernal equinox (i.e., the March equinox, one of the two opposing directions each termed an equinox; defining either defines both and the vernal equinox is the equinox used as the equatorial coordinate system's origin). Like the standard epoch, earlier standard equinoxes were used, generally used for reports/catalogs near in time to their respective epochs. For example, prior to standardization of the J2000.0 equinox, the B1950.0 equinox (analogously based on epoch B1950.0) was commonly used. The J2000.0 vernal equinox in the previous coordinates is B235726.22567-001641.9527.

Further reading:

Referenced by pages:
epoch J2000.0
J designator