Azimut
Azimut, from Arabic words: السمت, assamt means street, part or quarter, is the angle measurement in the spherical coordinate system. The vector of the observer to the observation point is projected perpendicular to the reference plane; The angle between the projected vector and the reference vector on the reference plane is azimuth. Examples of azimuths are in the measurement of star position. The star is the observation point, the reference plane is the horizon or the sea surface, and the reference vector is forwarded north. In this case, the azimuth is the angle between the north and the projection perpendicular to the star down in the horizon. Azimut is commonly measured in a degree unit. This concept is used in many applications including navigation, astronomy, engineering, mapping, mining and artillery.