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Horizontal Coordinate System

(az/el system, Alt/Az system, altazimuth system)
(celestial coordinate system based upon horizon and north)

The Horizontal Coordinate System (az/el system ,Alt/Az system, altazimuth system) is a spherical coordinate system used for directions in the Celestial Sphere, fixed to the horizon and north. It is key to observation from Earth, but time-dependent: the daily rotation of Earth produces the whole sky's constant minute-by-minute change, called the Diurnal Motion. Other coordinate systems avoid this.

Elements of the horizontal coordinate system:

  • Altitude - angle from the horizon.
  • Azimuth - angle eastward from north.
  • Zenith Distance - compliment of altitude, which can be used instead.

(coordinate system,horizon,celestial sphere,Earth)

Referenced by:
Celestial Coordinate System