Equinox (celestial coordinates): Difference between revisions

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==Besselian equinoxes/epochs==
A Besselian epoch, named after the German mathematician and astronomer [[Friedrich Bessel]] (1784–1846), is an epoch that is based on a ''Besselian year'' of 365.242198781 days, which is a [[tropical year]] measured at the point where the [[Sun]]'s longitude is exactly 280°. Since 1984, Besselian equinoxes and epochs have been superseded by [[#Julian epochs|Julian equinoxes and epochs]]. The current standard equinox and epoch is [[#J2000.0|J2000.0]], which is a Julian epoch.
The "J" in the prefix indicates that it is a Julian equinox/epoch rather than a Besselian equinox/epoch.
==External links==
*[http://csep10.phys.utk.edu/astr161/lect/time/coordinates.html Celestial Coordinate System, UTK]
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