def test_precessedgeocentric_loopback():
from_coo = PrecessedGeocentric(1 * u.deg,
2 * u.deg,
3 * u.AU,
obstime='2001-01-01',
equinox='2001-01-01')
# Change just the obstime
to_frame = PrecessedGeocentric(obstime='2001-06-30', equinox='2001-01-01')
explicit_coo = from_coo.transform_to(ICRS()).transform_to(to_frame)
implicit_coo = from_coo.transform_to(to_frame)
# Confirm that the explicit transformation changes the coordinate
assert not allclose(explicit_coo.ra, from_coo.ra, rtol=1e-10)
assert not allclose(explicit_coo.dec, from_coo.dec, rtol=1e-10)
assert not allclose(explicit_coo.distance, from_coo.distance, rtol=1e-10)
# Confirm that the loopback matches the explicit transformation
assert_allclose(explicit_coo.ra, implicit_coo.ra, rtol=1e-10)
assert_allclose(explicit_coo.dec, implicit_coo.dec, rtol=1e-10)
assert_allclose(explicit_coo.distance, implicit_coo.distance, rtol=1e-10)
# Change just the equinox
to_frame = PrecessedGeocentric(obstime='2001-01-01', equinox='2001-06-30')
explicit_coo = from_coo.transform_to(ICRS()).transform_to(to_frame)
implicit_coo = from_coo.transform_to(to_frame)
# Confirm that the explicit transformation changes the direction but not the distance
assert not allclose(explicit_coo.ra, from_coo.ra, rtol=1e-10)
assert not allclose(explicit_coo.dec, from_coo.dec, rtol=1e-10)
assert allclose(explicit_coo.distance, from_coo.distance, rtol=1e-10)
# Confirm that the loopback matches the explicit transformation
assert_allclose(explicit_coo.ra, implicit_coo.ra, rtol=1e-10)
assert_allclose(explicit_coo.dec, implicit_coo.dec, rtol=1e-10)
assert_allclose(explicit_coo.distance, implicit_coo.distance, rtol=1e-10)
def TEME2ECI_pos(Pos_TEME, t):
T = Time(t, format='jd', scale='utc')
dist_vect = norm(Pos_TEME, axis=0)
ra_vect = np.arctan2(Pos_TEME[1], Pos_TEME[0])
dec_vect = np.arcsin(Pos_TEME[2] / dist_vect)
Pos_TEME_SC = PrecessedGeocentric(ra=ra_vect * u.rad,
dec=dec_vect * u.rad, distance=dist_vect * u.m, equinox=T, obstime=T)
Pos_ECI_SC = Pos_TEME_SC.transform_to(GCRS(obstime=T))
Pos_ECI = np.vstack(Pos_ECI_SC.cartesian.xyz.value)
return Pos_ECI
