Galactic coordinate system

Galactic coordinate system is one of the coordinate systems that are used in the spherical astronomy (see Astronomical coordinate systems). It is helpful for the study of the Milky Way system.

Reference plane of the galactic coordinate system, the plane of the Milky Way, zero is the sun. Galactic length is measured in the counterclockwise direction in this plane. The galactic latitude is measured perpendicular to this, positive and negative to the north to the south.

In 1958 the present galactic coordinates were introduced internationally and defined with the equatorial coordinates ( Based on the Bessel epoch B1950.0 ) of the Galactic North Pole by = 12h 49min and = 27.40 °. The galactic longitude is counted starting from the galactic center = 17h 42.4min and = -28.92 °, the galactic plane is inclined by 62.6 ° from the celestial equator. After determination of the galactic coordinate system has been found, however, that this " zero meridian " of the galactic coordinates * misses the actual galactic center at the location of the radio source Sagittarius A is about 0.07 °. The the 1958 galactic coordinates are still used further.