def test_equatorial_to_galactic(self):
"""
start with a pulsar in equatorial coordinates
convert to Galactic and make sure the positions are consistent
then apply the space motion to the equatorial object & convert to Galactic
compare that to the Galactic object w/ space motion
"""
# make a test SkyCoord object
# make sure it has obstime and distance supplied
# to use it for conversions as well
J0613_icrs = self.modelJ0613.coords_as_ICRS()
J0613_icrs_now = utils.add_dummy_distance(J0613_icrs)
J0613_galactic = self.modelJ0613.coords_as_GAL()
J0613_galactic_now = utils.add_dummy_distance(J0613_galactic)
newepoch = self.modelJ0613.POSEPOCH.quantity.mjd + 100
# what I get converting within astropy
J0613_galactic_comparison = J0613_icrs_now.transform_to(
astropy.coordinates.Galactic)
sep = J0613_galactic_now.separation(J0613_galactic_comparison)
msg = (
"Equatorial to Galactic conversion for now failed with separation %.1e arcsec"
% sep.arcsec)
assert sep < 1e-5 * u.arcsec, msg
print(J0613_icrs_now)
print(J0613_galactic_now)
J0613_icrs = self.modelJ0613.coords_as_ICRS(epoch=newepoch)
# what I get converting within astropy
J0613_galactic_comparison = J0613_icrs.transform_to(
astropy.coordinates.Galactic)
J0613_galactic_then = utils.remove_dummy_distance(
J0613_galactic_now.apply_space_motion(
new_obstime=astropy.time.Time(newepoch, format="mjd")))
sep = J0613_galactic_then.separation(J0613_galactic_comparison)
msg = (
"Equatorial to Galactic conversion for +100d failed with separation %.1e arcsec"
% sep.arcsec)
assert sep < 1e-6 * u.arcsec, msg
def test_ecliptic_to_galactic(self):
"""
start with a pulsar in ecliptic coordinates
convert to Galactic and make sure the positions are consistent
then apply the space motion to the ecliptic object & convert to Galactic
compare that to the Galactic object w/ space motion
"""
# make a test SkyCoord object
# make sure it has obstime and distance supplied
# to use it for conversions as well
B1855_ECL = self.modelB1855.coords_as_ECL()
B1855_ECL_now = utils.add_dummy_distance(B1855_ECL)
B1855_galactic = self.modelB1855.coords_as_GAL()
B1855_galactic_now = utils.add_dummy_distance(B1855_galactic)
newepoch = self.modelB1855.POSEPOCH.quantity.mjd + 100
# what I get converting within astropy
B1855_galactic_comparison = B1855_ECL_now.transform_to(
astropy.coordinates.Galactic)
sep = B1855_galactic_now.separation(B1855_galactic_comparison)
msg = (
"Ecliptic to Galactic conversion for now failed with separation %.1e arcsec"
% sep.arcsec)
assert sep < 1e-9 * u.arcsec, msg
B1855_ECL = self.modelB1855.coords_as_ECL(epoch=newepoch)
# what I get converting within astropy
B1855_galactic_comparison = B1855_ECL.transform_to(
astropy.coordinates.Galactic)
B1855_galactic_then = utils.remove_dummy_distance(
B1855_galactic_now.apply_space_motion(
new_obstime=astropy.time.Time(
newepoch, scale="tdb", format="mjd")))
sep = B1855_galactic_then.separation(B1855_galactic_comparison)
msg = (
"Ecliptic to Galactic conversion for +100d failed with separation %.1e arcsec"
% sep.arcsec)
assert sep < 1e-9 * u.arcsec, msg
def get_psr_coords(self, epoch=None):
"""Returns pulsar sky coordinates as an astropy ecliptic coordinate instance.
Parameters
----------
epoch: `astropy.time.Time` or Float, optional
new epoch for position. If Float, MJD(TDB) is assumed
Returns
-------
position
PulsarEcliptic SkyCoord object optionally with proper motion applied
If epoch (MJD) is specified, proper motion is included to return
the position at the given epoch.
"""
try:
obliquity = OBL[self.ECL.value]
except KeyError:
raise ValueError(
"No obliquity " + str(self.ECL.value) + " provided. "
"Check your pint/datafile/ecliptic.dat file."
)
if epoch is None or (self.PMELONG.value == 0.0 and self.PMELAT.value == 0.0):
# Compute only once
return coords.SkyCoord(
obliquity=obliquity,
lon=self.ELONG.quantity,
lat=self.ELAT.quantity,
pm_lon_coslat=self.PMELONG.quantity,
pm_lat=self.PMELAT.quantity,
obstime=self.POSEPOCH.quantity,
frame=PulsarEcliptic,
)
else:
# Compute for each time because there is proper motion
if isinstance(epoch, Time):
newepoch = epoch
else:
newepoch = Time(epoch, scale="tdb", format="mjd")
position_now = add_dummy_distance(self.get_psr_coords())
position_then = remove_dummy_distance(
position_now.apply_space_motion(new_obstime=newepoch)
)
return position_then
def get_psr_coords(self, epoch=None):
"""Returns pulsar sky coordinates as an astropy ICRS object instance.
Parameters
----------
epoch: `astropy.time.Time` or Float, optional
new epoch for position. If Float, MJD is assumed
Returns
-------
position
ICRS SkyCoord object optionally with proper motion applied
If epoch (MJD) is specified, proper motion is included to return
the position at the given epoch.
"""
if epoch is None or (self.PMRA.value == 0.0
and self.PMDEC.value == 0.0):
dRA = 0.0 * u.hourangle
dDEC = 0.0 * u.deg
broadcast = 1
newepoch = self.POSEPOCH.quantity
return coords.SkyCoord(
ra=self.RAJ.quantity + dRA,
dec=self.DECJ.quantity + dDEC,
pm_ra_cosdec=self.PMRA.quantity * broadcast,
pm_dec=self.PMDEC.quantity * broadcast,
obstime=newepoch,
frame=coords.ICRS,
)
else:
if isinstance(epoch, Time):
newepoch = epoch
else:
newepoch = Time(epoch, format="mjd")
position_now = add_dummy_distance(self.get_psr_coords())
position_then = remove_dummy_distance(
position_now.apply_space_motion(new_obstime=newepoch))
return position_then
def test_proper_motion(self):
"""
use the PINT and astropy proper motion calculations and compare
"""
# make a test SkyCoord object
# make sure it has obstime and distance supplied
# to use it for conversions as well
J0613_icrs = self.modelJ0613.coords_as_ICRS()
J0613_icrs_now = utils.add_dummy_distance(J0613_icrs)
newepoch = self.modelJ0613.POSEPOCH.quantity.mjd + 100
# now do it for a future epoch
J0613_icrs = self.modelJ0613.coords_as_ICRS(epoch=newepoch)
# and use the coordinates now but use astropy's space motion
print(
J0613_icrs_now.apply_space_motion(new_obstime=astropy.time.Time(
newepoch, scale="tdb", format="mjd")))
J0613_icrs_now_to_then = utils.remove_dummy_distance(
J0613_icrs_now.apply_space_motion(new_obstime=astropy.time.Time(
newepoch, scale="tdb", format="mjd")))
sep = J0613_icrs.separation(J0613_icrs_now_to_then)
msg = (
"Applying proper motion for +100d failed with separation %.1e arcsec"
% sep.arcsec)
assert sep < 1e-9 * u.arcsec, msg
# make sure it can support newepoch supplied as a Time object
newepoch = astropy.time.Time(newepoch, format="mjd")
J0613_icrs = self.modelJ0613.coords_as_ICRS(epoch=newepoch)
J0613_icrs_now_to_then = utils.remove_dummy_distance(
J0613_icrs_now.apply_space_motion(new_obstime=newepoch))
sep = J0613_icrs.separation(J0613_icrs_now_to_then)
msg = (
"Applying proper motion for +100d failed with separation %.1e arcsec"
% sep.arcsec)
assert sep < 1e-9 * u.arcsec, msg