<p><a href="https://astronomy.stackexchange.com/users/2365/james-kilfiger">James Kilfiger</a> has suggested me to expand my comment as answer, and here it is:</p>

<p>Searching I have found the data in the international astronomical union website. In <a href="http://iau.org/public/themes/constellations" rel="nofollow noreferrer">http://iau.org/public/themes/constellations</a> you can find a TXT for each constellation with vertex's R.A. and DEC.</p>

<p>At the end of that page there is an explanation about the fields on that text files. Their coordinates are J2000.</p>

CC BY-SA 3.0
2016-06-01T06:19:31.953Z
2016-06-01T06:19:31.953Z
2017-04-13T12:59:07.017Z
VansFannel
<p>They are defined on the coordinate grid of 1875; precession has shifted and rotated them since then, and a map for the present epoch must account for that. In addition to the vertices, you may need to interpolate a few points along the edges.
<a href="http://cdsarc.u-strasbg.fr/viz-bin/Cat?VI/49" rel="nofollow">Davenhall and Leggett 1989</a> provide boundary coordinates for epochs 1875 and 2000.
For determining which constellation contains a given point, <a href="http://cdsarc.u-strasbg.fr/viz-bin/Cat?VI/42" rel="nofollow">Roman 1987</a> provides regions and lookup code.</p>

CC BY-SA 3.0
2016-05-30T22:27:18.330Z
2016-05-30T22:27:18.330Z
Mike G
<p>I'm developing a planetarium software and I need the R.A. and DEC that represents every constellation area in the sky. I think I only need R.A. and DEC for each vertex.</p>

<p>Where can I find it?</p>

<p>I'm searching on Internet and I can't find it. Maybe because I'm not doing the right search.</p>

CC BY-SA 3.0
2016-05-29T15:52:10.437Z
I think is here: http://www.iau.org/public/themes/constellations/. There is a TXT for each constellation with vertex's R.A. and DEC.
VansFannel
CC BY-SA 3.0
2016-05-31T16:48:38.690Z
That should be expanded into an answer.
James K
<constellations>
R.A. and DEC. for Constellation area vertices
VansFannel
# R.A. and DEC. for Constellation area vertices

(Asked by: username_0 on 2016-05-29)

I'm developing a planetarium software and I need the R.A. and DEC that represents every constellation area in the sky. I think I only need R.A. and DEC for each vertex.

Where can I find it?

I'm searching on Internet and I can't find it. Maybe because I'm not doing the right search.

**Tags:** constellations

> **Comments:**
> **username_0**: I think is here: http://www.iau.org/public/themes/constellations/. There is a TXT for each constellation with vertex's R.A. and DEC.  
> **username_1**: That should be expanded into an answer.  

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## 2 answers

### Answer by username_0 on 2016-06-01. Score: 1 | Accepted answer

[username_1ilfiger](https://astronomy.stackexchange.com/users/2365/james-kilfiger) has suggested me to expand my comment as answer, and here it is:

Searching I have found the data in the international astronomical union website. In <http://iau.org/public/themes/constellations> you can find a TXT for each constellation with vertex's R.A. and DEC.

At the end of that page there is an explanation about the fields on that text files. Their coordinates are J2000.


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### Answer by username_2 on 2016-05-30. Score: 0

They are defined on the coordinate grid of 1875; precession has shifted and rotated them since then, and a map for the present epoch must account for that. In addition to the vertices, you may need to interpolate a few points along the edges.
[Davenhall and Leggett 1989](http://cdsarc.u-strasbg.fr/viz-bin/Cat?VI/49) provide boundary coordinates for epochs 1875 and 2000.
For determining which constellation contains a given point, [Roman 1987](http://cdsarc.u-strasbg.fr/viz-bin/Cat?VI/42) provides regions and lookup code.


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