<p>This is the reply I got from the US Naval Observatory itself:</p>

<blockquote>
  <p>No, we do not have that transformation in NOVAS.  Generally, altitude and azimuth are not determined to very high accuracy, so using them to obtain RA and Dec, which are much more precisely defined and measured, does not make a lot of sense.</p>
</blockquote>

CC BY-SA 3.0
2015-03-27T23:45:08.247Z
2015-03-27T23:45:08.247Z
tearvisus
<p>I'm using NOVAS 3.1. I know that I can convert equatorial coordinates to horizontal coordinates using the <code>equ2hor</code> function.</p>

<p>Is it possible to make NOVAS do the inverse transformation: from horizontal to equatorial? There is no <code>hor2equ</code>, but maybe some other function implements this functionality?</p>

<fundamental-astronomy><coordinate><software>
How to convert horizontal coordinates using NOVAS?
tearvisus
# How to convert horizontal coordinates using NOVAS?

(Asked by: username_0 on 2015-03-23)

I'm using NOVAS 3.1. I know that I can convert equatorial coordinates to horizontal coordinates using the `equ2hor` function.

Is it possible to make NOVAS do the inverse transformation: from horizontal to equatorial? There is no `hor2equ`, but maybe some other function implements this functionality?

**Tags:** fundamental-astronomy, coordinate, software

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## 1 answers

### Answer by username_0 on 2015-03-27. Score: 0 | Accepted answer

This is the reply I got from the US Naval Observatory itself:

> No, we do not have that transformation in NOVAS. Generally, altitude and azimuth are not determined to very high accuracy, so using them to obtain RA and Dec, which are much more precisely defined and measured, does not make a lot of sense.


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