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astropy / coordinates-benchmark

Accuracy Benchmarks of different coordinate conversion codes. Maintainers: @astrojuanlu, @astrofrog, and @cdeil
https://www.astropy.org/coordinates-benchmark/summary.html
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Add celestial conversion check for different epochs of observation #12

Open cdeil opened 12 years ago

cdeil commented 12 years ago

Like @dsberry said in https://github.com/astropy/coordinates-benchmark/pull/4#issuecomment-10753477 :

2) In the table, for the "Epoch of observation", you probably want to use the same value (J2000) for all systems, at least initially. Having said that, you have a problem if any of the coordinate packages do not allow the epoch of observation to be specified. For instance, I'm not sure what the current implementation of astropy coords assumes about the epoch of observation. I understand Erik has agreed that an ObsTime property is needed, but I presume he hasn't yet added it.

6) A further development could be to add more tag names for other combinations, like "fk5_J2010_J2012.34" meaning equatorial fk5 with respect to equinox of J2010, observed at J2012.34. Converting to and from systems with non-default values for equinox and epoch should test more bits of the code. Although of course the total number of tests could become difficult to handle.

I agree we should keep the number of tests small. We could just test astropy (once obstime is available) against pyast and I don't think we need all systems here.

astrofrog commented 11 years ago

I think we should start thinking about adding a test or two for arbitrary equinox and epoch of observation. For example, at the moment, I'm testing the following with Kapteyn to check the implementation of FK4 -> FK5 in Astropy

before = (celestial.equatorial, celestial.fk4_no_e, "B1930", "B1966_OBS")
after = (celestial.equatorial, celestial.fk5, "J2030")
coords = celestial.sky2sky(before, after, 45., 46.)

@cdeil - I'm not sure how to best do this, because as you were saying above, we should keep the number of tests small. Maybe we could just compare against kapteyn and pyAST? (or even just PyAST)