The declination of the Sun or any celestial body is one of the coordinates in the equatorial coordinate system corresponding to the latitude on the Earth. Its the angular distance δ measured in degrees north or south of the celestial equator
It is equivalent to the the latitude of the Geographical Position (GP) or subsolar point of the Sun, where the line from the Sun to the centre of the Earth intersects the surface.
The Greenwich Hour Angle (GHA) is the longitude of the Geographical Position (GP) of the Sun measured westwards from the Greenwich meridian.
