The azimuth angle in astronomy is the arc of the horizon measured clockwise from the south point or north point of the horizon to the point on the horizon intersected by the object's line of altitude. The azimuth is measured in degrees.
In navigation, the azimuth angle is measured to the point where a vertical circle through a given heavenly body intersects the horizon. The vector from an observer, which is the origin, to the point of interest is projected perpendicularly onto a reference plane. Usually, azimuths or compass bearings are stated in a system, in which either north or south can be zero, and the angle may be measured clockwise or anticlockwise from zero.