def test_hcrs_hgs_different_obstime():
# Test whether the HCRS->HGS transformation handles a change in obstime the same way as forcing
# a HCRS loopback in Astropy
time1 = Time('2001-01-01')
time2 = Time('2001-02-01')
coord = HCRS(1*u.km, 2*u.km, 3*u.km, representation_type='cartesian', obstime=time1)
out_frame = HeliographicStonyhurst(obstime=time2)
sunpy_coord = coord.transform_to(out_frame)
astropy_coord = coord.transform_to(HCRS(obstime=time2)).transform_to(out_frame)
assert quantity_allclose(sunpy_coord.cartesian.xyz, astropy_coord.cartesian.xyz)
def gei_to_hme(geicoord, hmeframe):
"""
Convert from Geocentric Earth Equatorial to Heliocentric Mean Ecliptic
"""
if geicoord.obstime is None:
raise ConvertError("To perform this transformation, the coordinate"
" frame needs a specified `obstime`.")
# Use an intermediate frame of HME at the GEI observation time
int_frame = HeliocentricMeanEcliptic(obstime=geicoord.obstime, equinox=geicoord.equinox)
# Get the Sun-Earth vector in the intermediate frame
sun_earth = HCRS(_sun_earth_icrf(int_frame.obstime), obstime=int_frame.obstime)
sun_earth_int = sun_earth.transform_to(int_frame).cartesian
# Rotate from Earth equatorial to ecliptic
rot_matrix = _rotation_matrix_obliquity(int_frame.equinox)
earth_object_int = geicoord.cartesian.transform(rot_matrix)
# Find the Sun-object vector in the intermediate frame
sun_object_int = sun_earth_int + earth_object_int
int_coord = int_frame.realize_frame(sun_object_int)
# Convert to the final frame through HCRS
return int_coord.transform_to(HCRS(obstime=int_coord.obstime)).transform_to(hmeframe)
def hme_to_gei(hmecoord, geiframe):
"""
Convert from Heliocentric Mean Ecliptic to Geocentric Earth Equatorial
"""
if geiframe.obstime is None:
raise ConvertError("To perform this transformation, the coordinate"
" frame needs a specified `obstime`.")
# Use an intermediate frame of HME at the GEI observation time, through HCRS
int_frame = HeliocentricMeanEcliptic(obstime=geiframe.obstime,
equinox=geiframe.equinox)
int_coord = hmecoord.transform_to(
HCRS(obstime=int_frame.obstime)).transform_to(int_frame)
# Get the Sun-Earth vector in the intermediate frame
sun_earth = HCRS(_sun_earth_icrf(int_frame.obstime),
obstime=int_frame.obstime)
sun_earth_int = sun_earth.transform_to(int_frame).cartesian
# Find the Earth-object vector in the intermediate frame
earth_object_int = int_coord.cartesian - sun_earth_int
# Rotate from ecliptic to Earth equatorial
rot_matrix = matrix_transpose(_rotation_matrix_obliquity(
int_frame.equinox))
newrepr = earth_object_int.transform(rot_matrix)
return geiframe.realize_frame(newrepr)
def test_hcrs_hgs_reversibility():
# Test whether the HCRS->HGS transformation is reversed by the HGS->HCRS transformation
time1 = Time('2001-01-01')
time2 = Time('2001-02-01')
coord = HCRS(1*u.km, 2*u.km, 3*u.km, representation_type='cartesian', obstime=time1)
new_coord = coord.transform_to(HeliographicStonyhurst(obstime=time2)).transform_to(coord)
assert quantity_allclose(coord.cartesian.xyz, new_coord.cartesian.xyz)
def HCI2ECI_pos(Pos_HCI, t):
# Position & velocity relative to the sun
T = Time(t, format='jd', scale='utc')
Pos_HCRS = HCI2HCRS(Pos_HCI)
# TODO. HARD: had to remove it
#Vel_HCRS_rel = HCI2HCRS(Vel_HCI - EarthVelocity(t))
Pos_HCRS_SC = HCRS(x=Pos_HCRS[0]*u.m, y=Pos_HCRS[1]*u.m, z=Pos_HCRS[2]*u.m,
representation_type='cartesian', obstime=T)
Pos_ECI = np.vstack(Pos_HCRS_SC.transform_to(GCRS(obstime=T)).cartesian.xyz.value)
return Pos_ECI
def _rotation_matrix_hme_to_hee(hmeframe):
"""
Return the rotation matrix from HME to HEE at the same observation time
"""
# Get the Sun-Earth vector
sun_earth = HCRS(_sun_earth_icrf(hmeframe.obstime), obstime=hmeframe.obstime)
sun_earth_hme = sun_earth.transform_to(hmeframe).cartesian
# Rotate the Sun-Earth vector about the Z axis so that it lies in the XZ plane
rot_matrix = _rotation_matrix_reprs_to_xz_about_z(sun_earth_hme)
# Tilt the rotated Sun-Earth vector so that it is aligned with the X axis
tilt_matrix = _rotation_matrix_reprs_to_reprs(sun_earth_hme.transform(rot_matrix),
CartesianRepresentation(1, 0, 0))
return matrix_product(tilt_matrix, rot_matrix)
def hee_to_gse(heecoord, gseframe):
"""
Convert from Heliocentric Earth Ecliptic to Geocentric Solar Ecliptic
"""
# Use an intermediate frame of HEE at the GSE observation time
int_frame = HeliocentricEarthEcliptic(obstime=gseframe.obstime)
int_coord = heecoord.transform_to(int_frame)
# Get the Sun-Earth vector in the intermediate frame
sun_earth = HCRS(_sun_earth_icrf(int_frame.obstime), obstime=int_frame.obstime)
sun_earth_int = sun_earth.transform_to(int_frame).cartesian
# Find the Earth-object vector in the intermediate frame
earth_object_int = int_coord.cartesian - sun_earth_int
# Flip the vector in X and Y, but leave Z untouched
# (The additional transpose operations are to handle both scalar and array inputs)
newrepr = CartesianRepresentation((earth_object_int.xyz.T * [-1, -1, 1]).T)
return gseframe.realize_frame(newrepr)
