B1875.0

The B1875.0 epoch is used in astronomy.

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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 official constellation boundaries were defined in 1930 along the lines of right ascension and declination for this epoch.

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The "B" in the prefix indicates that it is a Besselian epoch, as opposed to a Julian epoch. The 1875 figure refers to the year 1875 whose mean equator and equinox are used to define right ascension and declination of celestial bodies. See precession.

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Epoch: The word epoch can mean either an interval of time, or a particular point in time used as a reference point....

Astronomy: :This article is about the science branch. For information about the magazine, see Astronomy (magazine)....

Right ascension: Right ascension (RA; symbol α: Greek letter alpha) is the astronomical term for one of the two coordinates of a point on the celestial sphere when using the equatorial coordinate system. The other coordinate is the declination. RA is comparable to longitude, measured from a zero point known as...