Given equatorial coordinates [img] scienceworld.wolfram.com/astronomy/gimg4.gif[/img] (declination) and [img] scienceworld.wolfram.com/astronomy/gimg4.gif[/img] (right ascension), the galactic coordinates (b, l), can be computed from the formulas



The first system was defined in 1932 using optical observations of the Milky Way Galaxy . The new system was defined in 1958 in terms of 21 cm observations of HI (Sullivan 1984, p. 140).