GalSim-developers / GalSim-developers/GalSim
define `origin` and `world_origin` for CelestialWCS classes?
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- Dominant language
- Python
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- 272
- Forks
- 121
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Description
@sidneymau and I were working on some DES stuff and ran into an issue where we need the point on the sphere about which a given a WCS uses the projection. We found that the GSFitsWCS class defines a .center property (but that its value was (0, 0) which did not make much sense to us).
However, ignoring that .center was a bit funny in our case, as far as I can tell
.centeris the point we want but is largely undocumented?- the
originandworld_originattributes are not defined
Is there a reason we couldn't set origin to CRPIX or similar and set world_origin to the tangent point on the sphere?
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Research direction
Start by reading the CelestialWCS classes and the GSFitsWCS .center property, then compare their existing coordinate conventions with CRPIX and the projection's tangent point. Define consistent meanings for origin and world_origin, and verify that the resulting behavior is documented and covered for the relevant CelestialWCS classes.
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Assessment
- Tech stack
- python
- Domain
- data
- Issue type
- Feature
- Difficulty
- 5/5
- Estimated time
- Over a week
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100