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get_moon does not support non-scalar times #5069
Description
get_moon is only tested with scalar times, and fails for non-scalar times,
In [16]: import numpy as np
In [17]: from astropy.coordinates import get_moon
In [18]: from astropy.time import Time
In [19]: import astropy.units as u
In [20]: get_moon(Time.now() + np.linspace(0, 1)*u.day)
---------------------------------------------------------------------------
ValueError Traceback (most recent call last)
<ipython-input-20-7d6db65d30c7> in <module>()
----> 1 get_moon(Time.now() + np.linspace(0, 1)*u.day)
/Users/bmmorris/anaconda/lib/python3.5/site-packages/astropy-1.2.dev15671-py3.5-macosx-10.5-x86_64.egg/astropy/coordinates/solar_system.py in get_moon(time, location, ephemeris)
376 """
377
--> 378 return get_body('moon', time, location=location, ephemeris=ephemeris)
379
380 get_moon.__doc__ += indent(_EPHEMERIS_NOTE)[4:]
/Users/bmmorris/anaconda/lib/python3.5/site-packages/astropy-1.2.dev15671-py3.5-macosx-10.5-x86_64.egg/astropy/coordinates/solar_system.py in get_body(body, time, location, ephemeris)
336 location = time.location
337
--> 338 cartrep = _get_apparent_body_position(body, time, ephemeris)
339 icrs = ICRS(cartrep)
340 if location is not None:
/Users/bmmorris/anaconda/lib/python3.5/site-packages/astropy-1.2.dev15671-py3.5-macosx-10.5-x86_64.egg/astropy/coordinates/solar_system.py in _get_apparent_body_position(body, time, ephemeris)
283 # used.
284 if ephemeris == 'builtin' and body.lower() == 'moon':
--> 285 return get_body_barycentric(body, time, ephemeris)
286
287 # Calculate position given approximate light travel time.
/Users/bmmorris/anaconda/lib/python3.5/site-packages/astropy-1.2.dev15671-py3.5-macosx-10.5-x86_64.egg/astropy/coordinates/solar_system.py in get_body_barycentric(body, time, ephemeris)
214 cartesian_position_body = earth_pv_bary[..., 0, :]
215 elif body == 'moon':
--> 216 cartesian_position_body = calc_moon(time).cartesian.xyz.to(u.au).value
217 else:
218 sun_bary = earth_pv_bary[..., 0, :] - earth_pv_helio[..., 0, :]
/Users/bmmorris/anaconda/lib/python3.5/site-packages/astropy-1.2.dev15671-py3.5-macosx-10.5-x86_64.egg/astropy/coordinates/orbital_elements.py in calc_moon(t)
245 equinox=t)
246
--> 247 return SkyCoord(ecliptic_coo.transform_to(ICRS))
/Users/bmmorris/anaconda/lib/python3.5/site-packages/astropy-1.2.dev15671-py3.5-macosx-10.5-x86_64.egg/astropy/coordinates/baseframe.py in transform_to(self, new_frame)
847 msg = 'Cannot transform from {0} to {1}'
848 raise ConvertError(msg.format(self.__class__, new_frame.__class__))
--> 849 return trans(self, new_frame)
850
851 def is_transformable_to(self, new_frame):
/Users/bmmorris/anaconda/lib/python3.5/site-packages/astropy-1.2.dev15671-py3.5-macosx-10.5-x86_64.egg/astropy/coordinates/transformations.py in __call__(self, fromcoord, toframe)
913
914 curr_toframe = t.tosys(**frattrs)
--> 915 curr_coord = t(curr_coord, curr_toframe)
916
917 # this is safe even in the case where self.transforms is empty, because
/Users/bmmorris/anaconda/lib/python3.5/site-packages/astropy-1.2.dev15671-py3.5-macosx-10.5-x86_64.egg/astropy/coordinates/transformations.py in __call__(self, fromcoord, toframe)
704
705 def __call__(self, fromcoord, toframe):
--> 706 res = self.func(fromcoord, toframe)
707 if not isinstance(res, self.tosys):
708 raise TypeError('the transformation function yielded {0} but '
/Users/bmmorris/anaconda/lib/python3.5/site-packages/astropy-1.2.dev15671-py3.5-macosx-10.5-x86_64.egg/astropy/coordinates/builtin_frames/ecliptic_transforms.py in geoecliptic_to_gcrs(from_coo, gcrs_frame)
42 @frame_transform_graph.transform(FunctionTransform, GeocentricTrueEcliptic, GCRS)
43 def geoecliptic_to_gcrs(from_coo, gcrs_frame):
---> 44 rmat = _ecliptic_rotation_matrix(from_coo.equinox)
45 newrepr = cartrepr_from_matmul(rmat, from_coo, transpose=True)
46 gcrs = GCRS(newrepr, obstime=from_coo.equinox)
/Users/bmmorris/anaconda/lib/python3.5/site-packages/astropy-1.2.dev15671-py3.5-macosx-10.5-x86_64.egg/astropy/coordinates/builtin_frames/ecliptic_transforms.py in _ecliptic_rotation_matrix(equinox)
27 rnpb = erfa.pnm06a(jd1, jd2)
28 obl = erfa.obl06(jd1, jd2)*u.radian
---> 29 return np.asarray(np.dot(rotation_matrix(obl, 'x'), rnpb))
30
31
/Users/bmmorris/anaconda/lib/python3.5/site-packages/astropy-1.2.dev15671-py3.5-macosx-10.5-x86_64.egg/astropy/coordinates/angles.py in rotation_matrix(angle, axis, unit)
716 return np.matrix(((1, 0, 0),
717 (0, c, s),
--> 718 (0, -s, c)))
719 else:
720 axis = np.asarray(axis)
/Users/bmmorris/anaconda/lib/python3.5/site-packages/numpy/matrixlib/defmatrix.py in __new__(subtype, data, dtype, copy)
268
269 # now convert data to an array
--> 270 arr = N.array(data, dtype=dtype, copy=copy)
271 ndim = arr.ndim
272 shape = arr.shape
ValueError: setting an array element with a sequence.
This is a blocker on the astroplan switch from PyEphem to astropy solar system ephemerides (i.e. astropy/astroplan#35).
Activity
[-]get_moon does not support vector times[/-][+]get_moon does not support non-scalar times[/+]astrofrog commentedon Jun 12, 2016
@bmorris3 - in the mean time, to avoid this being a blocker, maybe you could make a wrapper around astropy's
get_moonto automatically transform scalar times to 1-element arrays, then slice the result?StuartLittlefair commentedon Jun 13, 2016
@bmorris3 I've submitted a PR to fix this issue (#5085). You may still find that you have issues because you cannot currently use non-scalar times and a non-geocentric observer. i.e
works fine, but
clearly does not. A fix for #4926 is needed for the case above to work. I'll start on that next.
eteq commentedon Jun 15, 2016
Note that I checked and @bmorris3's example now works with #5085 merged. @bmorris3, if the problem #4926 is addressing is affecting you feel free to open another issue on that!