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separation fails with recursion error for some coordinates #4033
Description
This is a subtle bug that probably slipped through the tests because it depends on a particular set of inputs. Specifically, if you ask for the separation between two SkyCoord objects when both have a distance, you get a strange error:
>>> alb = SkyCoord.from_name('Albireo')
>>> alb_wdist = SkyCoord(alb, distance=133*u.pc)
>>> de = SkyCoord.from_name('Deneb')
>>> de_wdist = SkyCoord(de, distance=802*u.pc)
>>> aa = AltAz(location=EarthLocation(lat=45*u.deg, lon=0*u.deg), obstime='2010-1-1')
>>> alb_wdistaa = alb_wdist.transform_to(aa)
>>> de_wdistaa = de_wdist.transform_to(aa)
>>> de_wdistaa.separation(alb_wdistaa)
RuntimeError: maximum recursion depth exceeded while calling a Python objectThe particularly curious thing is that this does not happen if the one calling has no distance:
>>> deaa = de.transform_to(aa)
>>> albaa = alb.transform_to(aa)
>>> deaa.separation(albaa)
<Angle 22.28621055928645 deg>
>>> deaa.separation(alb_wdistaa)
<Angle [ 22.28621208] deg>
>>> alb_wdistaa.separation(deaa)
RuntimeError: maximum recursion depth exceeded while calling a Python objectThe second one there is probably related to #3920, so it's quite possible a fix for that will also fix this.
Activity
eteq commentedon Aug 3, 2015
cc @bmorris3 as the one who has a use case that triggered this (astropy/astroplan#39)