def _erfa_check(ira, idec, astrom):
"""
This function does the same thing the astropy layer is supposed to do, but
all in erfa
"""
cra, cdec = erfa.atciq(ira, idec, 0, 0, 0, 0, astrom)
az, zen, ha, odec, ora = erfa.atioq(cra, cdec, astrom)
alt = np.pi / 2 - zen
cra2, cdec2 = erfa.atoiq('A', az, zen, astrom)
ira2, idec2 = erfa.aticq(cra2, cdec2, astrom)
dct = locals()
del dct['astrom']
return dct
def _erfa_check(ira, idec, astrom):
"""
This function does the same thing the astropy layer is supposed to do, but
all in erfa
"""
cra, cdec = erfa.atciq(ira, idec, 0, 0, 0, 0, astrom)
az, zen, ha, odec, ora = erfa.atioq(cra, cdec, astrom)
alt = np.pi/2-zen
cra2, cdec2 = erfa.atoiq('A', az, zen, astrom)
ira2, idec2 = erfa.aticq(cra2, cdec2, astrom)
dct = locals()
del dct['astrom']
return dct
def altaz_to_cirs(altaz_coo, cirs_frame):
usrepr = altaz_coo.represent_as(UnitSphericalRepresentation)
az = usrepr.lon.to_value(u.radian)
zen = PIOVER2 - usrepr.lat.to_value(u.radian)
lon, lat, height = altaz_coo.location.to_geodetic('WGS84')
xp, yp = get_polar_motion(altaz_coo.obstime)
# first set up the astrometry context for ICRS<->CIRS at the altaz_coo time
jd1, jd2 = get_jd12(altaz_coo.obstime, 'utc')
astrom = erfa.apio13(
jd1,
jd2,
get_dut1utc(altaz_coo.obstime),
lon.to_value(u.radian),
lat.to_value(u.radian),
height.to_value(u.m),
xp,
yp, # polar motion
# all below are already in correct units because they are QuantityFrameAttribues
altaz_coo.pressure.value,
altaz_coo.temperature.value,
altaz_coo.relative_humidity.value,
altaz_coo.obswl.value)
# the 'A' indicates zen/az inputs
cirs_ra, cirs_dec = erfa.atoiq('A', az, zen, astrom) * u.radian
if isinstance(altaz_coo.data, UnitSphericalRepresentation
) or altaz_coo.cartesian.x.unit == u.one:
cirs_at_aa_time = CIRS(ra=cirs_ra,
dec=cirs_dec,
distance=None,
obstime=altaz_coo.obstime)
else:
# treat the output of atoiq as an "astrometric" RA/DEC, so to get the
# actual RA/Dec from the observers vantage point, we have to reverse
# the vector operation of cirs_to_altaz (see there for more detail)
loccirs = altaz_coo.location.get_itrs(
altaz_coo.obstime).transform_to(cirs_frame)
astrometric_rep = SphericalRepresentation(lon=cirs_ra,
lat=cirs_dec,
distance=altaz_coo.distance)
newrepr = astrometric_rep + loccirs.cartesian
cirs_at_aa_time = CIRS(newrepr, obstime=altaz_coo.obstime)
# this final transform may be a no-op if the obstimes are the same
return cirs_at_aa_time.transform_to(cirs_frame)
def altaz_to_cirs(altaz_coo, cirs_frame):
usrepr = altaz_coo.represent_as(UnitSphericalRepresentation)
az = usrepr.lon.to_value(u.radian)
zen = PIOVER2 - usrepr.lat.to_value(u.radian)
lon, lat, height = altaz_coo.location.to_geodetic('WGS84')
xp, yp = get_polar_motion(altaz_coo.obstime)
# first set up the astrometry context for ICRS<->CIRS at the altaz_coo time
jd1, jd2 = get_jd12(altaz_coo.obstime, 'utc')
astrom = erfa.apio13(jd1, jd2,
get_dut1utc(altaz_coo.obstime),
lon.to_value(u.radian), lat.to_value(u.radian),
height.to_value(u.m),
xp, yp, # polar motion
# all below are already in correct units because they are QuantityFrameAttribues
altaz_coo.pressure.value,
altaz_coo.temperature.value,
altaz_coo.relative_humidity.value,
altaz_coo.obswl.value)
# the 'A' indicates zen/az inputs
cirs_ra, cirs_dec = erfa.atoiq('A', az, zen, astrom)*u.radian
if isinstance(altaz_coo.data, UnitSphericalRepresentation) or altaz_coo.cartesian.x.unit == u.one:
cirs_at_aa_time = CIRS(ra=cirs_ra, dec=cirs_dec, distance=None,
obstime=altaz_coo.obstime)
else:
# treat the output of atoiq as an "astrometric" RA/DEC, so to get the
# actual RA/Dec from the observers vantage point, we have to reverse
# the vector operation of cirs_to_altaz (see there for more detail)
loccirs = altaz_coo.location.get_itrs(altaz_coo.obstime).transform_to(cirs_frame)
astrometric_rep = SphericalRepresentation(lon=cirs_ra, lat=cirs_dec,
distance=altaz_coo.distance)
newrepr = astrometric_rep + loccirs.cartesian
cirs_at_aa_time = CIRS(newrepr, obstime=altaz_coo.obstime)
# this final transform may be a no-op if the obstimes are the same
return cirs_at_aa_time.transform_to(cirs_frame)