Add position angle functionality #1

cdeil opened this Issue Aug 13, 2012 · 5 comments


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cdeil commented Aug 13, 2012

It would be nice if you could add the following functionality to pyephem:

  • Compute the position angle between two points in a given coordinate system (namely Equatorial or Galactic or AltAz).
  • Transform a position angle in one coordinate system (e.g. AltAz) to another (e.g. Galactic).

When implemented please mention it in this stackoverflow question:


brandon-rhodes commented Aug 14, 2012

Thank you for writing up this issue! I should have some spare cycles next week — after this weekend's DjangoDash — to look at creating a solution.

brandon-rhodes added a commit that referenced this issue Aug 15, 2012

Merge pull request #1 from aisipos/docstrings
Add some docstrings for more basic types.


cdeil commented Apr 13, 2014

I'm hoping this feature will become in astropy.coordinates (astropy/astropy#2311).


brandon-rhodes commented May 29, 2014

Instead of trying to do that in PyEphem — whose mission I have now more narrowly defined as simply wrapping the old astronomy logic inside of libastro — I am going to attempt this functionality inside of Skyfield instead, so I am going to close this ticket and focus my future work there, since it is a pure-Python astronomy library (except for needing NumPy) that should be easier to advance and improve:


brandon-rhodes commented May 29, 2014

(And, feel free to drop a link here if you did get around to adding this to astropy!)


cdeil commented May 29, 2014

Position angle computation is available in astropy here, position angle transformation to other coordinate systems is not.

If you do implement this in skyfield, that would be great.

klaussnd pushed a commit to Pix4D/pyephem that referenced this issue Jan 4, 2018

Merged in master-add-install-step (pull request #1)
Install step to correctly setup @rpath on mac

Approved-by: Luis Díaz Más <>
Approved-by: Olivier Dormond <>
Approved-by: David Sinuela <>
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