Altitude angle

Definition

• Altitude (alt. or altitude angle), sometimes referred to as elevation (el. or elevation angle) or apparent height, is the angle between the object and the observer's local horizon. For visible objects, it is an angle between 0° and 90°.
• Azimuth (az.) is the angle of the object around the horizon, usually measured from true north and increasing eastward. Exceptions are, for example, ESO's FITS convention where it is measured from the south and increasing westward, or the FITS convention of the Sloan Digital Sky Survey where it is measured from the south and increasing eastward.