The geocentric coordinate system consisting of right ascension (or hour angle; the angle between an object's longitude and the First Point in Aries measured eastward along the celestial equator) and declination (the angle above or below the celestial equator, from to -90°). The conversions from elevation (altitude)-azimuth coordinates to equatorial coordinates hour angle H and declination for an observer at latitude L are



Given galactic coordinates (b, l), the equatorial (declination) and coordinates (right ascension) can be computed from the formulas