One of the coordinates used to define position on the celestial sphere in the equatorial coordinate system . It is the equivalent of longitude on the Earth but is measured in hours, minutes and seconds of time eastwards from the zero point, which is taken as the intersection of the celestial equator and the ecliptic, known as the First Point of Aries. In a spherical coordinate system, angular distance round the equator or a circle parallel to it from an arbitrary zero point. In the celestial equatorial coordinate system, the counterpart of longitude is right ascension. One of the coordinates used to define position on the celestial sphere in the equatorial coordinate system.
Declination is the equivalent of latitude on the Earth.
It is the angular distance, measured in degrees, north or south of the celestial equator. Northerly declinations are positive and southerly ones negative. Angular distance north or south of the equator in a spherical coordinate system. In celestial equatorial coordinates, the counterpart of latitude is declination.