def test_rotating_vector_into_frame():
et_seconds = 259056665.1855896
ts = load.timescale()
t = ts.tdb_jd(T0 + et_seconds / 3600. / 24.0)
pc = PlanetaryConstants()
pc.read_text(load('moon_080317.tf'))
pc.read_binary(load('moon_pa_de421_1900-2050.bpc'))
# Example from "moon_080317.tf" (the raw vector is taken from a
# tweaked version of the script in the file that uses "J2000"):
vector = ICRF(
np.array([
2.4798273371071659e+05, -2.6189996683651494e+05,
-1.2455830876097400e+05
]) / AU_KM)
vector.t = t
meter = 1e-3
frame = pc.build_frame_named('MOON_PA_DE421')
result = vector.frame_xyz(frame)
assert max(abs(result.km - [379908.634, 33385.003, -12516.8859])) < meter
relative_frame = pc.build_frame_named('MOON_ME_DE421')
result = vector.frame_xyz(relative_frame)
assert max(abs(result.km - [379892.825, 33510.118, -12661.5278])) < meter
def test_frame_rotations_for_mean_of_date():
ts = api.load.timescale()
t = ts.utc(2020, 11, 21)
p = ICRF((1.1, 1.2, 1.3), t=t)
lat, lon, distance1 = p.frame_latlon(true_equator_and_equinox_of_date)
# Verify that the frame_latlon() coordinates match those from the
# more conventional radec() call.
ra, dec, distance2 = p.radec(epoch='date')
assert abs(lat.arcseconds() - dec.arcseconds()) < 1e-6
assert abs(lon.arcseconds() - ra.arcseconds()) < 1e-6
assert abs(distance1.au - distance2.au) < 1e-15
# Now that we know the coordinates are good, we can use them to
# rebuild a trusted x,y,z vector with which to test frame_xyz().
x1, y1, z1 = from_spherical(distance1.au, lat.radians, lon.radians)
x2, y2, z2 = p.frame_xyz(true_equator_and_equinox_of_date).au
assert abs(x1 - x2) < 1e-15
assert abs(y1 - y2) < 1e-15
assert abs(z1 - z2) < 1e-15