JThe J2000.0 epoch is used in astronomy. It is precisely Julian date 2451545.0 TT, or January 1 2000, 12h TT. This is equivalent to January 1 2000, 11:59:27.816 TAI or January 1 2000, 11:58:55.816 UTC. Since the right ascension and declination of stars are constantly changing due to precession, astronomers always specify these with reference to a particular epoch. The earlier epoch that was in standard use was the B1950.0 epoch. The "J" in the prefix indicates that it is a Julian epoch, as opposed to a Besselian epoch. External links
Categories: Astronomy |
|
This article is licensed under the GNU Free Documentation License. It uses material from Wikipedia article. Browse Wikipedia for more information. |