[Debian-astro-maintainers] Bug#935563: astropy 3.2.1 breaks sunpy

[Steve Langasek]

Source: astropy
Version: 3.2.1-1
Severity: serious
Justification: autopkgtest regressions block migration
Affects: sunpy/0.9.6-2
User: ubuntu-devel at lists.ubuntu.com
Usertags: origin-ubuntu eoan autopkgtest

Hi Ole,

The sunpy autopkgtests fail with new astropy 3.2.1-1, and considering the
failing autopkgtest is one specifically intended to test an error-prone
astropy transformation (according to the comments), this looks to me like it
may be a genuine regression in astropy that's caught by sunpy:

[...]
=================================== FAILURES ===================================
________________________________ test_hgs_hcrs _________________________________

    def test_hgs_hcrs():
        # This test checks the HGS->HCRS transformation by transforming from HGS to
        # HeliocentricTrueEcliptic (HTE).  It will fail if there are errors in Astropy's
        # HCRS->ICRS or ICRS->HTE transformations.
    
        # Use published HGS coordinates in the Astronomical Almanac (2013), pages C6-C7
        obstime = Time('2013-01-28')
        earth_hgs = SkyCoord(0*u.deg, -5.73*u.deg, 0.9848139*u.AU, frame=HeliographicStonyhurst,
                             obstime=obstime)
    
        # Transform to HTE at observation-time equinox
        earth_hte = earth_hgs.transform_to(HeliocentricTrueEcliptic(equinox=obstime))
    
        # Validate against published values from the Astronomical Almanac (2013), page C6 per page E2
        # The dominant source of inaccuracy is the limited precision of the published B0 used above
>       assert quantity_allclose(earth_hte.lon, Angle('308d13m30.51s') - 180*u.deg, atol=5*u.arcsec)
E       assert False
E        +  where False = quantity_allclose(<Longitude 128.23007468 deg>, (<Angle 308.22514167 deg> - (180 * Unit("deg"))), atol=(5 * Unit("arcsec")))
E        +    where <Longitude 128.23007468 deg> = <SkyCoord (HeliocentricTrueEcliptic: equinox=2013-01-28 00:00:00.000, obstime=2013-01-28 00:00:00.000): (lon, lat, distance) in (deg, deg, AU)\n    (128.23007468, 0.00023427, 0.9848139)>.lon
E        +    and   <Angle 308.22514167 deg> = Angle('308d13m30.51s')
E        +    and   Unit("deg") = u.deg
E        +    and   Unit("arcsec") = u.arcsec

/usr/lib/python3/dist-packages/sunpy/coordinates/tests/test_transformations.py:146: AssertionError
[...]

(https://ci.debian.net/data/autopkgtest/testing/amd64/s/sunpy/2801123/log.gz)

Opening a bug so that this is documented in the BTS (and so it can be
reassigned if I'm wrong about which package is to blame).

-- 
Steve Langasek                   Give me a lever long enough and a Free OS
Debian Developer                   to set it on, and I can move the world.
Ubuntu Developer                                   https://www.debian.org/
slangasek at ubuntu.com                                     vorlon at debian.org
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 833 bytes
Desc: not available
URL: <http://alioth-lists.debian.net/pipermail/debian-astro-maintainers/attachments/20190823/5d7361f5/attachment.sig>