Definition:Azimuth (Astronomy)

Definition

Let $X$ be a point on the celestial sphere.

The spherical angle between the principal vertical circle and the vertical circle on which $X$ lies is the azimuth of $X$.

The azimuth is usually measured in degrees, $0 \degrees$ to $180 \degrees$ either west or east, depending on whether $X$ lies on the eastern or western hemisphere of the celestial sphere.

Also defined as

Some sources define the azimuth as from $0 \degrees$ to $360 \degrees$ measured east of the principal vertical circle, that is, clockwise.

Sources

• 1976: W.M. Smart: Textbook on Spherical Astronomy (6th ed.) ... (previous) ... (next): Chapter $\text {II}$. The Celestial Sphere: $18$. Altitude and azimuth.
• 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): azimuth: 2.
• 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): azimuth: 2.
• 2014: Christopher Clapham and James Nicholson: The Concise Oxford Dictionary of Mathematics (5th ed.) ... (previous) ... (next): azimuth
• 2021: Richard Earl and James Nicholson: The Concise Oxford Dictionary of Mathematics (6th ed.) ... (previous) ... (next): azimuth