<p>You use <a href="http://en.wikipedia.org/wiki/Spherical_trigonometry" rel="noreferrer">Spherical Trigonometry</a></p>

<p>Given $A_1$ and $A_2$ are the respective azimuthal coordinates of the two objects, and $a_1$, $a_2$ their respective altitudes,</p>

<p>the angular seperation $\theta$ is given by</p>

<p>$$\cos \theta = \sin a_1 \sin a_2 + \cos a_1 \cos a_2 \cos (A_1-A_2)$$</p>

CC BY-SA 3.0
2014-05-25T23:21:15.070Z
2014-05-26T13:33:08.340Z
2014-05-26T13:33:08.340Z
Cheeku
<p>Given the horizontal coordinates of two objects in the sky, how does one go about calculating the angular separation between them?</p>

<positional-astronomy>
Calculating Angular Distance
ruadath
# Calculating Angular Distance

(Asked by: username_0 on 2014-05-25)

Given the horizontal coordinates of two objects in the sky, how does one go about calculating the angular separation between them?

**Tags:** positional-astronomy

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## 1 answers

### Answer by username_1 on 2014-05-25. Score: 7 | Accepted answer

You use [Spherical Trigonometry](http://en.wikipedia.org/wiki/Spherical_trigonometry)

Given $A\_1$ and $A\_2$ are the respective azimuthal coordinates of the two objects, and $a\_1$, $a\_2$ their respective altitudes,

the angular seperation $\theta$ is given by

$$\cos \theta = \sin a\_1 \sin a\_2 + \cos a\_1 \cos a\_2 \cos (A\_1-A\_2)$$


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