def test_tete_transforms():
"""
We test the TETE transforms for proper behaviour here.
The TETE transforms are tested for accuracy against JPL Horizons in
test_solar_system.py. Here we are looking to check for consistency and
errors in the self transform.
"""
loc = EarthLocation.from_geodetic("-22°57'35.1", "-67°47'14.1", 5186 * u.m)
time = Time('2020-04-06T00:00')
p, v = loc.get_gcrs_posvel(time)
gcrs_frame = GCRS(obstime=time, obsgeoloc=p, obsgeovel=v)
moon = SkyCoord(169.24113968 * u.deg,
10.86086666 * u.deg,
358549.25381755 * u.km,
frame=gcrs_frame)
tete_frame = TETE(obstime=time, location=loc)
# need to set obsgeoloc/vel explicity or skycoord behaviour over-writes
tete_geo = TETE(obstime=time, location=EarthLocation(*([0, 0, 0] * u.km)))
# test self-transform by comparing to GCRS-TETE-ITRS-TETE route
tete_coo1 = moon.transform_to(tete_frame)
tete_coo2 = moon.transform_to(tete_geo)
assert_allclose(tete_coo1.separation_3d(tete_coo2),
0 * u.mm,
atol=1 * u.mm)
# test TETE-ITRS transform by comparing GCRS-CIRS-ITRS to GCRS-TETE-ITRS
itrs1 = moon.transform_to(CIRS()).transform_to(ITRS())
itrs2 = moon.transform_to(TETE()).transform_to(ITRS())
# this won't be as close since it will round trip through ICRS until
# we have some way of translating between the GCRS obsgeoloc/obsgeovel
# attributes and the CIRS location attributes
assert_allclose(itrs1.separation_3d(itrs2), 0 * u.mm, atol=100 * u.mm)
# test round trip GCRS->TETE->GCRS
new_moon = moon.transform_to(TETE()).transform_to(moon)
assert_allclose(new_moon.separation_3d(moon), 0 * u.mm, atol=1 * u.mm)
# test round trip via ITRS
tete_rt = tete_coo1.transform_to(
ITRS(obstime=time)).transform_to(tete_coo1)
assert_allclose(tete_rt.separation_3d(tete_coo1), 0 * u.mm, atol=1 * u.mm)
# ensure deprecated routine remains consistent
# make sure test raises warning!
with pytest.warns(AstropyDeprecationWarning, match='The use of'):
tete_alt = _apparent_position_in_true_coordinates(moon)
assert_allclose(tete_coo1.separation_3d(tete_alt),
0 * u.mm,
atol=100 * u.mm)
def test_de432s_moon(self):
astropy = get_moon(self.t, ephemeris='de432s')
horizons = self.horizons['moon']
# convert to true equator and equinox
astropy = _apparent_position_in_true_coordinates(astropy)
# Assert sky coordinates are close.
assert (astropy.separation(horizons) <
de432s_separation_tolerance_moon)
# Assert distances are close.
assert_quantity_allclose(astropy.distance, horizons.distance,
atol=de432s_distance_tolerance)
def test_erfa_planet(self, body, sep_tol, dist_tol):
"""Test predictions using erfa/plan94.
Accuracies are maximum deviations listed in erfa/plan94.c, for Jupiter and
Mercury, and that quoted in Meeus "Astronomical Algorithms" (1998) for the Moon.
"""
astropy = get_body(body, self.t, ephemeris='builtin')
horizons = self.horizons[body]
# convert to true equator and equinox
astropy = _apparent_position_in_true_coordinates(astropy)
# Assert sky coordinates are close.
assert astropy.separation(horizons) < sep_tol
# Assert distances are close.
assert_quantity_allclose(astropy.distance, horizons.distance,
atol=dist_tol)
def test_erfa_planet(self, body, sep_tol, dist_tol):
"""Test predictions using erfa/plan94.
Accuracies are maximum deviations listed in erfa/plan94.c.
"""
# Add uncertainty in position of Earth
dist_tol = dist_tol + 1300 * u.km
astropy = get_body(body, self.t, ephemeris='builtin')
horizons = self.horizons[body]
# convert to true equator and equinox
astropy = _apparent_position_in_true_coordinates(astropy)
# Assert sky coordinates are close.
assert astropy.separation(horizons) < sep_tol
# Assert distances are close.
assert_quantity_allclose(astropy.distance, horizons.distance,
atol=dist_tol)
def test_positions_skyfield():
"""
Test positions against those generated by skyfield.
"""
t = Time('1980-03-25 00:00')
location = None
# skyfield ephemeris
planets = load('de421.bsp')
ts = load.timescale()
mercury, jupiter, moon = planets['mercury'], planets[
'jupiter barycenter'], planets['moon']
earth = planets['earth']
skyfield_t = ts.from_astropy(t)
if location is not None:
earth = earth.topos(latitude_degrees=location.lat.to_value(u.deg),
longitude_degrees=location.lon.to_value(u.deg),
elevation_m=location.height.to_value(u.m))
skyfield_mercury = earth.at(skyfield_t).observe(mercury).apparent()
skyfield_jupiter = earth.at(skyfield_t).observe(jupiter).apparent()
skyfield_moon = earth.at(skyfield_t).observe(moon).apparent()
if location is not None:
obsgeoloc, obsgeovel = location.get_gcrs_posvel(t)
frame = GCRS(obstime=t, obsgeoloc=obsgeoloc, obsgeovel=obsgeovel)
else:
frame = GCRS(obstime=t)
ra, dec, dist = skyfield_mercury.radec(epoch='date')
skyfield_mercury = SkyCoord(ra.to(u.deg),
dec.to(u.deg),
distance=dist.to(u.km),
frame=frame)
ra, dec, dist = skyfield_jupiter.radec(epoch='date')
skyfield_jupiter = SkyCoord(ra.to(u.deg),
dec.to(u.deg),
distance=dist.to(u.km),
frame=frame)
ra, dec, dist = skyfield_moon.radec(epoch='date')
skyfield_moon = SkyCoord(ra.to(u.deg),
dec.to(u.deg),
distance=dist.to(u.km),
frame=frame)
moon_astropy = get_moon(t, location, ephemeris='de430')
mercury_astropy = get_body('mercury', t, location, ephemeris='de430')
jupiter_astropy = get_body('jupiter', t, location, ephemeris='de430')
# convert to true equator and equinox
jupiter_astropy = _apparent_position_in_true_coordinates(jupiter_astropy)
mercury_astropy = _apparent_position_in_true_coordinates(mercury_astropy)
moon_astropy = _apparent_position_in_true_coordinates(moon_astropy)
assert (moon_astropy.separation(skyfield_moon) <
skyfield_angular_separation_tolerance)
assert (moon_astropy.separation_3d(skyfield_moon) <
skyfield_separation_tolerance)
assert (jupiter_astropy.separation(skyfield_jupiter) <
skyfield_angular_separation_tolerance)
assert (jupiter_astropy.separation_3d(skyfield_jupiter) <
skyfield_separation_tolerance)
assert (mercury_astropy.separation(skyfield_mercury) <
skyfield_angular_separation_tolerance)
assert (mercury_astropy.separation_3d(skyfield_mercury) <
skyfield_separation_tolerance)
def test_positions_skyfield():
"""
Test positions against those generated by skyfield.
"""
t = Time('1980-03-25 00:00')
location = None
# skyfield ephemeris
planets = load('de421.bsp')
ts = load.timescale()
mercury, jupiter, moon = planets['mercury'], planets['jupiter barycenter'], planets['moon']
earth = planets['earth']
skyfield_t = ts.from_astropy(t)
if location is not None:
earth = earth.topos(latitude_degrees=location.lat.to_value(u.deg),
longitude_degrees=location.lon.to_value(u.deg),
elevation_m=location.height.to_value(u.m))
skyfield_mercury = earth.at(skyfield_t).observe(mercury).apparent()
skyfield_jupiter = earth.at(skyfield_t).observe(jupiter).apparent()
skyfield_moon = earth.at(skyfield_t).observe(moon).apparent()
if location is not None:
obsgeoloc, obsgeovel = location.get_gcrs_posvel(t)
frame = GCRS(obstime=t, obsgeoloc=obsgeoloc, obsgeovel=obsgeovel)
else:
frame = GCRS(obstime=t)
ra, dec, dist = skyfield_mercury.radec(epoch='date')
skyfield_mercury = SkyCoord(ra.to(u.deg), dec.to(u.deg), distance=dist.to(u.km),
frame=frame)
ra, dec, dist = skyfield_jupiter.radec(epoch='date')
skyfield_jupiter = SkyCoord(ra.to(u.deg), dec.to(u.deg), distance=dist.to(u.km),
frame=frame)
ra, dec, dist = skyfield_moon.radec(epoch='date')
skyfield_moon = SkyCoord(ra.to(u.deg), dec.to(u.deg), distance=dist.to(u.km),
frame=frame)
moon_astropy = get_moon(t, location, ephemeris='de430')
mercury_astropy = get_body('mercury', t, location, ephemeris='de430')
jupiter_astropy = get_body('jupiter', t, location, ephemeris='de430')
# convert to true equator and equinox
jupiter_astropy = _apparent_position_in_true_coordinates(jupiter_astropy)
mercury_astropy = _apparent_position_in_true_coordinates(mercury_astropy)
moon_astropy = _apparent_position_in_true_coordinates(moon_astropy)
assert (moon_astropy.separation(skyfield_moon) <
skyfield_angular_separation_tolerance)
assert (moon_astropy.separation_3d(skyfield_moon) < skyfield_separation_tolerance)
assert (jupiter_astropy.separation(skyfield_jupiter) <
skyfield_angular_separation_tolerance)
assert (jupiter_astropy.separation_3d(skyfield_jupiter) <
skyfield_separation_tolerance)
assert (mercury_astropy.separation(skyfield_mercury) <
skyfield_angular_separation_tolerance)
assert (mercury_astropy.separation_3d(skyfield_mercury) <
skyfield_separation_tolerance)
