<p>Azimuth is conventionally calculated as a degree value between 0 (inclusive) and 360 (exclusive). <strong>North</strong> is assigned 0 (also by convention), which puts <strong>East</strong> at 90, <strong>South</strong> at 180, and <strong>West</strong> at 270.</p>

<p>Sometimes 0 is set to <strong>South</strong> intead of <strong>North</strong>. This is the traditional means of measuring solar azimuth, even though <strong>North</strong> is the most accepted convention.</p>

<p>Positive azimuths are noted when measuring east of 0, whether 0 is <strong>South</strong> or <strong>North</strong>. Negative azimuths are noted when measuring west of 0.</p>

<p><strong>Sources:</strong></p>

<ul>
<li><a href="http://www.susdesign.com/popups/sunangle/azimuth.php" rel="noreferrer">Azimuth Angle - Sustainable by Design</a></li>
<li><a href="http://en.wikipedia.org/wiki/Solar_azimuth_angle" rel="noreferrer">Solar azimuth angle - Wikipedia</a></li>
<li><a href="http://www.astro.cornell.edu/academics/courses/astro201/alt_az.htm" rel="noreferrer">Altitude and Azimuth - Martha Haynes, Cornell</a></li>
</ul>

CC BY-SA 3.0
2013-09-26T14:30:39.233Z
2013-10-14T22:02:27.207Z
2013-10-14T22:02:27.207Z
called2voyage
<p>There are many indeed. </p>

<p>It may be specified from South westwards(0° to 360°), or from North eastwards and westwards(180° to -180°).</p>

<p>The most popular one, as used by Roy and Clarke in "Astronomy : Principles and Practices" is to measure the azimuth from North eastwards 0° to 360°. For a southern hemisphere observer, this system changes to from South eastwards 0° to 360°.</p>

<p>With so much confusion, how do professional astronomers go about it? They simply specify the system they are using in a given document. Doesn't cause much trouble since the differences in all of the systems is by an angle of 180° or 360°. It just causes sign changes in all formula.</p>

CC BY-SA 3.0
2013-09-26T14:24:00.253Z
2013-09-26T14:24:00.253Z
Cheeku
<p>For a time, I thought Azimuth is always direction in degrees, 0 for local, geographic north, 90 for east etc.</p>

<p>Then, trying to observe moonrise I downloaded an app that gave azimuth in values between (if I recall correctly) -180 and 180, and I think "0" corresponded to south. I tried to read up on that and found very little fragmented information. I found other resources that frustrated me with numbers greater than 360, or provided values commonly associated with "West" for azimuth of moonrise and generally it took a bit of searching to find something with plain "degrees from north"</p>

<p>Could someone either post or provide a link to a comprehensive guide to various azimuth angle systems, when and where they are in use, and how to recognize which one is used?</p>

CC BY-SA 3.0
2013-10-14T23:40:14.710Z
Just to add to answers, since you mention you saw values greater than 360, those would likely be in _gon_ or [gradian](https://en.wikipedia.org/wiki/Grad_(angle)) and go from 0 to 400. But you always have to pay attention to the unit as well, not just the figure. On top of degrees (°) and gradians (gon), some other often cited units are radians (rad or ^c) and turns (rev or rot). Converting them is now easy enough by simply Googling for _`value unit to unit`_, e.g. [200 deg to rad](https://encrypted.google.com/search?q=200+deg+to+rad), or using [Wolfram Alpha](http://www.wolframalpha.com/). ;)
TildalWave
<navigation><azimuth>
What azimuth description systems are in use?
SF.
# What azimuth description systems are in use?

(Asked by: username_0 on 2013-09-26)

For a time, I thought Azimuth is always direction in degrees, 0 for local, geographic north, 90 for east etc.

Then, trying to observe moonrise I downloaded an app that gave azimuth in values between (if I recall correctly) -180 and 180, and I think "0" corresponded to south. I tried to read up on that and found very little fragmented information. I found other resources that frustrated me with numbers greater than 360, or provided values commonly associated with "West" for azimuth of moonrise and generally it took a bit of searching to find something with plain "degrees from north"

Could someone either post or provide a link to a comprehensive guide to various azimuth angle systems, when and where they are in use, and how to recognize which one is used?

**Tags:** navigation, azimuth

> **Comments:**
> **username_1**: Just to add to answers, since you mention you saw values greater than 360, those would likely be in _gon_ or [gradian](https://en.wikipedia.org/wiki/Grad_(angle)) and go from 0 to 400. But you always have to pay attention to the unit as well, not just the figure. On top of degrees (°) and gradians (gon), some other often cited units are radians (rad or ^c) and turns (rev or rot). Converting them is now easy enough by simply Googling for _`value unit to unit`_, e.g. [200 deg to rad](https://encrypted.google.com/search?q=200+deg+to+rad), or using [Wolfram Alpha](http://www.wolframalpha.com/). ;)  

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## 2 answers

### Answer by username_3 on 2013-09-26. Score: 8 | Accepted answer

There are many indeed.

It may be specified from South westwards(0° to 360°), or from North eastwards and westwards(180° to -180°).

The most popular one, as used by Roy and Clarke in "Astronomy : Principles and Practices" is to measure the azimuth from North eastwards 0° to 360°. For a southern hemisphere observer, this system changes to from South eastwards 0° to 360°.

With so much confusion, how do professional astronomers go about it? They simply specify the system they are using in a given document. Doesn't cause much trouble since the differences in all of the systems is by an angle of 180° or 360°. It just causes sign changes in all formula.


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### Answer by username_2 on 2013-09-26. Score: 7

Azimuth is conventionally calculated as a degree value between 0 (inclusive) and 360 (exclusive). **North** is assigned 0 (also by convention), which puts **East** at 90, **South** at 180, and **West** at 270.

Sometimes 0 is set to **South** intead of **North**. This is the traditional means of measuring solar azimuth, even though **North** is the most accepted convention.

Positive azimuths are noted when measuring east of 0, whether 0 is **South** or **North**. Negative azimuths are noted when measuring west of 0.

**Sources:**

* [Azimuth Angle - Sustainable by Design](http://www.susdesign.com/popups/sunangle/azimuth.php)
* [Solar azimuth angle - Wikipedia](http://en.wikipedia.org/wiki/Solar_azimuth_angle)
* [Altitude and Azimuth - Martha Haynes, Cornell](http://www.astro.cornell.edu/academics/courses/astro201/alt_az.htm)


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