quality:correction
In astronomy and celestial navigation, the hour angle is the dihedral angle between the meridian plane and the hour circle. It may be given in degrees, time, or rotations depending on the application.
The angle may be expressed as negative east of the meridian plane and positive west of the meridian plane, or as positive westward from 0° to 360°. The angle may be measured in degrees or in time, with 24h = 360° exactly.
In celestial navigation, the convention is to measure in degrees westward from the prime meridian, from the local meridian or from the first point of Aries. The hour angle is paired with the declination to fully specify the location of a point on the celestial sphere in the equatorial coordinate system.