"Tried to do is_equivalent_frame on something that isn't frame-like" error from MoonSeparationConstraint().compute_constraint() #567
Description
astropy-5.3.3
astroplan-0.9
import astroplan as ap
from astropy.time import Time
import astropy.units as u
from astropy.coordinates import SkyCoord
observer = ap.Observer.at_site('lasilla')
targets = [ap.FixedTarget(SkyCoord.from_name('Sirius'), name='Sirius')]
noon = Time("2023-06-06 12:00:00")
time_grid = ap.time_grid_from_range([noon,noon+1*u.day])
moon_constraint = ap.MoonSeparationConstraint(30*u.degree)
moon_ok_grid = moon_constraint.compute_constraint(time_grid, observer, [targets])
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
/var/folders/dl/tc85r2_j2v94kqhby3hvz4n00000gn/T/ipykernel_86529/2961427994.py in <module>
9 time_grid = ap.time_grid_from_range([noon,noon+1*u.day])
10 moon_constraint = ap.MoonSeparationConstraint(30*u.degree)
---> 11 moon_ok_grid = moon_constraint.compute_constraint(time_grid, observer, target)
~/miniconda3/lib/python3.9/site-packages/astroplan/constraints.py in compute_constraint(self, times, observer, targets)
596 # the former calculates the separation in the frame of the moon coord
597 # which is GCRS, and that is what we want.
--> 598 moon_separation = moon.separation(targets)
599
600 if self.min is None and self.max is not None:
~/miniconda3/lib/python3.9/site-packages/astropy/coordinates/sky_coordinate.py in separation(self, other)
1170 from .angle_utilities import angular_separation
1171
-> 1172 if not self.is_equivalent_frame(other):
1173 try:
1174 kwargs = (
~/miniconda3/lib/python3.9/site-packages/astropy/coordinates/sky_coordinate.py in is_equivalent_frame(self, other)
1129 else:
1130 # not a BaseCoordinateFrame nor a SkyCoord object
-> 1131 raise TypeError(
1132 "Tried to do is_equivalent_frame on something that isn't frame-like"
1133 )
TypeError: Tried to do is_equivalent_frame on something that isn't frame-like
I can get this working for a single target if I replace line 598 of constraints.py with ...
moon_separation = moon.separation(SkyCoord([target.coord for target in targets]))
... but I'm not sure why, and this does not work if targets is a list of more than one target.
-Pierre