def _make_reference_gwcs_wcs(fits_hdr):
hdr = fits.Header.fromfile(get_pkg_data_filename(fits_hdr))
fw = fitswcs.WCS(hdr)
unit_conv = Scale(1.0 / 3600.0, name='arcsec_to_deg_1D')
unit_conv = unit_conv & unit_conv
unit_conv.name = 'arcsec_to_deg_2D'
unit_conv_inv = Scale(3600.0, name='deg_to_arcsec_1D')
unit_conv_inv = unit_conv_inv & unit_conv_inv
unit_conv_inv.name = 'deg_to_arcsec_2D'
c2s = CartesianToSpherical(name='c2s', wrap_lon_at=180)
s2c = SphericalToCartesian(name='s2c', wrap_lon_at=180)
c2tan = ((Mapping((0, 1, 2), name='xyz') / Mapping(
(0, 0, 0), n_inputs=3, name='xxx')) | Mapping((1, 2), name='xtyt'))
c2tan.name = 'Cartesian 3D to TAN'
tan2c = (Mapping((0, 0, 1), n_inputs=2, name='xtyt2xyz') |
(Const1D(1, name='one') & Identity(2, name='I(2D)')))
tan2c.name = 'TAN to cartesian 3D'
tan2c.inverse = c2tan
c2tan.inverse = tan2c
aff = AffineTransformation2D(matrix=fw.wcs.cd)
offx = Shift(-fw.wcs.crpix[0])
offy = Shift(-fw.wcs.crpix[1])
s = 5e-6
scale = Scale(s) & Scale(s)
det2tan = (offx & offy) | scale | tan2c | c2s | unit_conv_inv
taninv = s2c | c2tan
tan = Pix2Sky_TAN()
n2c = RotateNative2Celestial(fw.wcs.crval[0], fw.wcs.crval[1], 180)
wcslin = unit_conv | taninv | scale.inverse | aff | tan | n2c
sky_frm = cf.CelestialFrame(reference_frame=coord.ICRS())
det_frm = cf.Frame2D(name='detector')
v2v3_frm = cf.Frame2D(name="v2v3",
unit=(u.arcsec, u.arcsec),
axes_names=('x', 'y'),
axes_order=(0, 1))
pipeline = [(det_frm, det2tan), (v2v3_frm, wcslin), (sky_frm, None)]
gw = gwcs.WCS(input_frame=det_frm,
output_frame=sky_frm,
forward_transform=pipeline)
gw.crpix = fw.wcs.crpix
gw.crval = fw.wcs.crval
gw.bounding_box = ((-0.5, fw.pixel_shape[0] - 0.5),
(-0.5, fw.pixel_shape[1] - 0.5))
return gw
def compute_va_effects(velocity_x, velocity_y, velocity_z, ra, dec):
""" Computes constant scale factor due to velocity aberration as well as
corrected ``RA`` and ``DEC`` values.
Parameters
----------
velocity_x, velocity_y, velocity_z: float
The components of the velocity of JWST, in km / s with respect to
the Sun. These are celestial coordinates, with x toward the
vernal equinox, y toward right ascension 90 degrees and declination
0, z toward the north celestial pole.
ra, dec: float
The right ascension and declination of the target (or some other
point, such as the center of a detector) in the barycentric coordinate
system. The equator and equinox should be the same as the coordinate
system for the velocity.
Returns
-------
scale_factor: float
Multiply the nominal image scale (e.g. in degrees per pixel) by
this value to obtain the image scale corrected for the "aberration
of starlight" due to the velocity of JWST with respect to the Sun.
apparent_ra: float
Apparent star position in the moving telescope frame.
apparent_dec: float
Apparent star position in the moving telescope frame.
"""
beta = np.array([velocity_x, velocity_y, velocity_z]) / SPEED_OF_LIGHT
beta2 = np.dot(beta, beta) # |beta|^2
if beta2 == 0.0:
logger.warning('Observatory speed is zero. Setting VA scale to 1.0')
return 1.0, ra, dec
u = np.asanyarray(SphericalToCartesian()(ra, dec))
beta_u = np.dot(beta, u)
igamma = np.sqrt(1.0 - beta2) # inverse of usual gamma
scale_factor = (1.0 + beta_u) / igamma
# Algorithm below is from Colin Cox notebook.
# Also see: Instrument Science Report OSG-CAL-97-06 by Colin Cox (1997).
u_corr = (igamma * u + beta *
(1.0 + (1.0 - igamma) * beta_u / beta2)) / (1.0 + beta_u)
apparent_ra, apparent_dec = CartesianToSpherical()(*u_corr)
return scale_factor, apparent_ra, apparent_dec
def v23tosky(input_model, wrap_v2_at=180, wrap_lon_at=360):
v2_ref = input_model.meta.wcsinfo.v2_ref / 3600
v3_ref = input_model.meta.wcsinfo.v3_ref / 3600
roll_ref = input_model.meta.wcsinfo.roll_ref
ra_ref = input_model.meta.wcsinfo.ra_ref
dec_ref = input_model.meta.wcsinfo.dec_ref
angles = np.array([v2_ref, -v3_ref, roll_ref, dec_ref, -ra_ref])
axes = "zyxyz"
rot = RotationSequence3D(angles, axes_order=axes)
# The sky rotation expects values in deg.
# This should be removed when models work with quantities.
m = ((Scale(1 / 3600) & Scale(1 / 3600)) | SphericalToCartesian(wrap_lon_at=wrap_v2_at)
| rot | CartesianToSpherical(wrap_lon_at=wrap_lon_at))
m.name = 'v23tosky'
return m
def _tpcorr_init(v2_ref, v3_ref, roll_ref):
s2c = SphericalToCartesian(name='s2c', wrap_lon_at=180)
c2s = CartesianToSpherical(name='c2s', wrap_lon_at=180)
unit_conv = Scale(1.0 / 3600.0, name='arcsec_to_deg_1D')
unit_conv = unit_conv & unit_conv
unit_conv.name = 'arcsec_to_deg_2D'
unit_conv_inv = Scale(3600.0, name='deg_to_arcsec_1D')
unit_conv_inv = unit_conv_inv & unit_conv_inv
unit_conv_inv.name = 'deg_to_arcsec_2D'
affine = AffineTransformation2D(name='tp_affine')
affine_inv = AffineTransformation2D(name='tp_affine_inv')
rot = RotationSequence3D([v2_ref, -v3_ref, roll_ref],
'zyx',
name='det_to_optic_axis')
rot_inv = rot.inverse
rot_inv.name = 'optic_axis_to_det'
# projection submodels:
c2tan = ((Mapping((0, 1, 2), name='xyz') / Mapping(
(0, 0, 0), n_inputs=3, name='xxx')) | Mapping((1, 2), name='xtyt'))
c2tan.name = 'Cartesian 3D to TAN'
tan2c = (Mapping((0, 0, 1), n_inputs=2, name='xtyt2xyz') |
(Const1D(1, name='one') & Identity(2, name='I(2D)')))
tan2c.name = 'TAN to cartesian 3D'
total_corr = (unit_conv | s2c | rot | c2tan | affine | tan2c | rot_inv
| c2s | unit_conv_inv)
total_corr.name = 'JWST tangent-plane linear correction. v1'
inv_total_corr = (unit_conv | s2c | rot | c2tan | affine_inv | tan2c
| rot_inv | c2s | unit_conv_inv)
inv_total_corr.name = 'Inverse JWST tangent-plane linear correction. v1'
# TODO
# re-enable circular inverse definitions once
# https://github.com/spacetelescope/asdf/issues/744 or
# https://github.com/spacetelescope/asdf/issues/745 are resolved.
#
# inv_total_corr.inverse = total_corr
total_corr.inverse = inv_total_corr
return total_corr
def test_v23_to_sky():
"""
Test taken from INS report.
"""
ra_ref = 165 # in deg
dec_ref = 54 # in deg
v2_ref = -503.654472 / 3600 # in deg
v3_ref = -318.742464 / 3600 # in deg
r0 = 37 # in deg
v2 = 210 # in deg
v3 = -75 # in deg
expected_ra_dec = (107.12810484789563, -35.97940247128502) # in deg
angles = [v2_ref, -v3_ref, r0, dec_ref, -ra_ref]
axes = "zyxyz"
rot = RotationSequence3D(angles, axes_order=axes)
v2s = SphericalToCartesian() | rot | CartesianToSpherical()
radec = v2s(v2, v3)
assert_allclose(radec, expected_ra_dec, atol=1e-10)
def _make_gwcs_wcs(fits_hdr):
hdr = fits.Header.fromfile(get_pkg_data_filename(fits_hdr))
fw = fitswcs.WCS(hdr)
a_order = hdr['A_ORDER']
a_coeff = {}
for i in range(a_order + 1):
for j in range(a_order + 1 - i):
key = 'A_{:d}_{:d}'.format(i, j)
if key in hdr:
a_coeff[key] = hdr[key]
b_order = hdr['B_ORDER']
b_coeff = {}
for i in range(b_order + 1):
for j in range(b_order + 1 - i):
key = 'B_{:d}_{:d}'.format(i, j)
if key in hdr:
b_coeff[key] = hdr[key]
cx = {"c" + k[2:]: v for k, v in a_coeff.items()}
cy = {"c" + k[2:]: v for k, v in b_coeff.items()}
sip_distortion = ((Shift(-fw.wcs.crpix[0]) & Shift(-fw.wcs.crpix[1]))
| Mapping((0, 1, 0, 1))
| (polynomial.Polynomial2D(a_order, **cx, c1_0=1)
& polynomial.Polynomial2D(b_order, **cy, c0_1=1))
| (Shift(fw.wcs.crpix[0]) & Shift(fw.wcs.crpix[1])))
y, x = np.indices(fw.array_shape)
unit_conv = Scale(1.0 / 3600.0, name='arcsec_to_deg_1D')
unit_conv = unit_conv & unit_conv
unit_conv.name = 'arcsec_to_deg_2D'
unit_conv_inv = Scale(3600.0, name='deg_to_arcsec_1D')
unit_conv_inv = unit_conv_inv & unit_conv_inv
unit_conv_inv.name = 'deg_to_arcsec_2D'
c2s = CartesianToSpherical(name='c2s', wrap_lon_at=180)
s2c = SphericalToCartesian(name='s2c', wrap_lon_at=180)
c2tan = ((Mapping((0, 1, 2), name='xyz') / Mapping(
(0, 0, 0), n_inputs=3, name='xxx')) | Mapping((1, 2), name='xtyt'))
c2tan.name = 'Cartesian 3D to TAN'
tan2c = (Mapping((0, 0, 1), n_inputs=2, name='xtyt2xyz') |
(Const1D(1, name='one') & Identity(2, name='I(2D)')))
tan2c.name = 'TAN to cartesian 3D'
tan2c.inverse = c2tan
c2tan.inverse = tan2c
aff = AffineTransformation2D(matrix=fw.wcs.cd)
offx = Shift(-fw.wcs.crpix[0])
offy = Shift(-fw.wcs.crpix[1])
s = 5e-6
scale = Scale(s) & Scale(s)
sip_distortion |= (offx & offy) | scale | tan2c | c2s | unit_conv_inv
taninv = s2c | c2tan
tan = Pix2Sky_TAN()
n2c = RotateNative2Celestial(fw.wcs.crval[0], fw.wcs.crval[1], 180)
wcslin = unit_conv | taninv | scale.inverse | aff | tan | n2c
sky_frm = cf.CelestialFrame(reference_frame=coord.ICRS())
det_frm = cf.Frame2D(name='detector')
v2v3_frm = cf.Frame2D(name="v2v3",
unit=(u.arcsec, u.arcsec),
axes_names=('x', 'y'),
axes_order=(0, 1))
pipeline = [(det_frm, sip_distortion), (v2v3_frm, wcslin), (sky_frm, None)]
gw = gwcs.WCS(input_frame=det_frm,
output_frame=sky_frm,
forward_transform=pipeline)
gw.crpix = fw.wcs.crpix
gw.crval = fw.wcs.crval
gw.bounding_box = ((-0.5, fw.pixel_shape[0] - 0.5),
(-0.5, fw.pixel_shape[1] - 0.5))
# sanity check:
for _ in range(100):
x = np.random.randint(1, fw.pixel_shape[0])
y = np.random.randint(1, fw.pixel_shape[1])
assert np.allclose(gw(x, y),
fw.all_pix2world(x, y, 1),
rtol=0,
atol=1e-11)
return gw
Licensed under a 3-clause BSD style license - see LICENSE.rst
"""
import math
import numpy as np
from astropy.modeling import Model, Parameter
from astropy.modeling.models import AffineTransformation2D, Identity
from astropy import coordinates as coord
from astropy import units as u
import gwcs
from gwcs.geometry import CartesianToSpherical, SphericalToCartesian
from tweakwcs.tpwcs import TPWCS, JWSTgWCS
_S2C = SphericalToCartesian(name='s2c', wrap_lon_at=180)
_C2S = CartesianToSpherical(name='c2s', wrap_lon_at=180)
class DummyTPWCS(TPWCS):
def set_correction(self,
matrix=[[1, 0], [0, 1]],
shift=[0, 0],
ref_tpwcs=None,
meta=None,
**kwargs):
super().set_correction(matrix=matrix,
shift=shift,
ref_tpwcs=ref_tpwcs,
meta=meta,
**kwargs)