Definition:Horizontal Coordinate System

Definition

The horizontal coordinate system is an astronomical coordinate system in which measurements are based on the celestial horizon.

Hence a point on the celestial sphere is located by means of $2$ angular measurements:

the azimuth $A$, which is the angular distance measured eastwards along the celestial horizon from the north point

the altitude $h$, which is the angular distance measured north or south of the celestial horizon.

Also defined as

The horizontal coordinate system is sometimes defined using the zenith distance $\zeta$ instead of the altitude $h$.

Also see

• Results about the horizontal coordinate system can be found here.

Sources

• 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): horizontal coordinate system
• 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): horizontal coordinate system