def test_create_primary_beams_AZELGEO(self):
self.createVis()
for telescope in ['VLA', 'ASKAP', 'MID', 'MID_GAUSS', 'MID_GRASP', 'LOW']:
model = create_image_from_visibility(self.vis, cellsize=0.001, override_cellsize=False)
beam = create_pb(model, telescope=telescope, use_local=True)
assert numpy.max(beam.data) > 0.0
export_image_to_fits(beam, "%s/test_primary_beam_AZELGEO_%s.fits" % (self.dir, telescope))
def test_create_primary_beams(self):
self.createVis(config='LOWBD2', rmax=1000.0)
for telescope in ['VLA', 'ASKAP', 'MID', 'LOW']:
model = create_image_from_visibility(self.vis,
cellsize=0.001,
override_cellsize=False)
beam = create_pb(model, telescope=telescope)
assert numpy.max(beam.data) > 0.0
export_image_to_fits(
beam, "%s/test_primary_beam_%s.fits" % (self.dir, telescope))
def test_create_primary_beams_RADEC(self):
self.createVis()
for telescope in ['VLA', 'ASKAP', 'MID', 'LOW']:
model = create_image_from_visibility(self.vis,
cellsize=self.cellsize,
npixel=self.npixel,
override_cellsize=False)
beam = create_pb(model, telescope=telescope, use_local=False)
assert numpy.max(beam.data) > 0.0
export_image_to_fits(
beam,
"%s/test_primary_beam_RADEC_%s.fits" % (self.dir, telescope))
def create_unittest_components(model,
flux,
applypb=False,
telescope='LOW',
npixel=None,
scale=1.0,
single=False,
symmetric=False):
# Fill the visibility with exactly computed point sources.
if npixel == None:
_, _, _, npixel = model.data.shape
spacing_pixels = int(scale * npixel) // 4
log.info('Spacing in pixels = %s' % spacing_pixels)
if not symmetric:
centers = [(0.2, 1.1)]
else:
centers = list()
if not single:
centers.append([0.0, 0.0])
for x in numpy.linspace(-1.2, 1.2, 7):
if abs(x) > 1e-15:
centers.append([x, x])
centers.append([x, -x])
model_pol = model.polarisation_frame
# Make the list of components
rpix = model.wcs.wcs.crpix
components = []
for center in centers:
ix, iy = center
# The phase center in 0-relative coordinates is n // 2 so we centre the grid of
# components on ny // 2, nx // 2. The wcs must be defined consistently.
p = int(round(rpix[0] + ix * spacing_pixels * numpy.sign(model.wcs.wcs.cdelt[0]))), \
int(round(rpix[1] + iy * spacing_pixels * numpy.sign(model.wcs.wcs.cdelt[1])))
sc = pixel_to_skycoord(p[0], p[1], model.wcs, origin=1)
log.info("Component at (%f, %f) [0-rel] %s" % (p[0], p[1], str(sc)))
# Channel images
comp = create_skycomponent(direction=sc,
flux=flux,
frequency=model.frequency,
polarisation_frame=model_pol)
components.append(comp)
if applypb:
beam = create_pb(model, telescope=telescope)
components = apply_beam_to_skycomponent(components, beam)
return components
def create_low_test_skymodel_from_gleam(npixel=512,
polarisation_frame=PolarisationFrame(
"stokesI"),
cellsize=0.000015,
frequency=numpy.array([1e8]),
channel_bandwidth=numpy.array([1e6]),
phasecentre=None,
kind='cubic',
applybeam=True,
flux_limit=0.1,
flux_max=numpy.inf,
flux_threshold=1.0,
insert_method='Nearest',
telescope='LOW') -> SkyModel:
"""Create LOW test skymodel from the GLEAM survey
Stokes I is estimated from a cubic spline fit to the measured fluxes. The polarised flux is always zero.
See http://www.mwatelescope.org/science/gleam-survey The catalog is available from Vizier.
VIII/100 GaLactic and Extragalactic All-sky MWA survey (Hurley-Walker+, 2016)
GaLactic and Extragalactic All-sky Murchison Wide Field Array (GLEAM) survey. I: A low-frequency extragalactic
catalogue. Hurley-Walker N., et al., Mon. Not. R. Astron. Soc., 464, 1146-1167 (2017), 2017MNRAS.464.1146H
:param telescope:
:param npixel: Number of pixels
:param polarisation_frame: Polarisation frame (default PolarisationFrame("stokesI"))
:param cellsize: cellsize in radians
:param frequency:
:param channel_bandwidth: Channel width (Hz)
:param phasecentre: phasecentre (SkyCoord)
:param kind: Kind of interpolation (see scipy.interpolate.interp1d) Default: cubic
:param applybeam: Apply the primary beam?
:param flux_limit: Weakest component
:param flux_max: Maximum strength component to be included in components
:param flux_threshold: Split between components (brighter) and image (weaker)
:param insert_method: Nearest | PSWF | Lanczos
:return:
:return: SkyModel
"""
if phasecentre is None:
phasecentre = SkyCoord(ra=+15.0 * u.deg,
dec=-35.0 * u.deg,
frame='icrs',
equinox='J2000')
radius = npixel * cellsize
sc = create_low_test_skycomponents_from_gleam(
flux_limit=flux_limit,
polarisation_frame=polarisation_frame,
frequency=frequency,
phasecentre=phasecentre,
kind=kind,
radius=radius)
sc = filter_skycomponents_by_flux(sc, flux_max=flux_max)
if polarisation_frame is None:
polarisation_frame = PolarisationFrame("stokesI")
npol = polarisation_frame.npol
nchan = len(frequency)
shape = [nchan, npol, npixel, npixel]
w = WCS(naxis=4)
# The negation in the longitude is needed by definition of RA, DEC
w.wcs.cdelt = [
-cellsize * 180.0 / numpy.pi, cellsize * 180.0 / numpy.pi, 1.0,
channel_bandwidth[0]
]
w.wcs.crpix = [npixel // 2 + 1, npixel // 2 + 1, 1.0, 1.0]
w.wcs.ctype = ["RA---SIN", "DEC--SIN", 'STOKES', 'FREQ']
w.wcs.crval = [phasecentre.ra.deg, phasecentre.dec.deg, 1.0, frequency[0]]
w.naxis = 4
w.wcs.radesys = 'ICRS'
w.wcs.equinox = 2000.0
model = create_image_from_array(numpy.zeros(shape),
w,
polarisation_frame=polarisation_frame)
if applybeam:
beam = create_pb(model, telescope=telescope)
sc = apply_beam_to_skycomponent(sc, beam)
weaksc = filter_skycomponents_by_flux(sc, flux_max=flux_threshold)
brightsc = filter_skycomponents_by_flux(sc, flux_min=flux_threshold)
model = insert_skycomponent(model, weaksc, insert_method=insert_method)
log.info(
'create_low_test_skymodel_from_gleam: %d bright sources above flux threshold %.3f, %d weak sources below '
% (len(brightsc), flux_threshold, len(weaksc)))
return SkyModel(components=brightsc,
image=model,
mask=None,
gaintable=None)
def create_low_test_image_from_gleam(npixel=512,
polarisation_frame=PolarisationFrame(
"stokesI"),
cellsize=0.000015,
frequency=numpy.array([1e8]),
channel_bandwidth=numpy.array([1e6]),
phasecentre=None,
kind='cubic',
applybeam=False,
flux_limit=0.1,
flux_max=numpy.inf,
flux_min=-numpy.inf,
radius=None,
insert_method='Nearest') -> Image:
"""Create LOW test image from the GLEAM survey
Stokes I is estimated from a cubic spline fit to the measured fluxes. The polarised flux is always zero.
See http://www.mwatelescope.org/science/gleam-survey The catalog is available from Vizier.
VIII/100 GaLactic and Extragalactic All-sky MWA survey (Hurley-Walker+, 2016)
GaLactic and Extragalactic All-sky Murchison Wide Field Array (GLEAM) survey. I: A low-frequency extragalactic
catalogue. Hurley-Walker N., et al., Mon. Not. R. Astron. Soc., 464, 1146-1167 (2017), 2017MNRAS.464.1146H
:param npixel: Number of pixels
:param polarisation_frame: Polarisation frame (default PolarisationFrame("stokesI"))
:param cellsize: cellsize in radians
:param frequency:
:param channel_bandwidth: Channel width (Hz)
:param phasecentre: phasecentre (SkyCoord)
:param kind: Kind of interpolation (see scipy.interpolate.interp1d) Default: linear
:return: Image
"""
if phasecentre is None:
phasecentre = SkyCoord(ra=+15.0 * u.deg,
dec=-35.0 * u.deg,
frame='icrs',
equinox='J2000')
if radius is None:
radius = npixel * cellsize / numpy.sqrt(2.0)
sc = create_low_test_skycomponents_from_gleam(
flux_limit=flux_limit,
polarisation_frame=polarisation_frame,
frequency=frequency,
phasecentre=phasecentre,
kind=kind,
radius=radius)
sc = filter_skycomponents_by_flux(sc, flux_min=flux_min, flux_max=flux_max)
if polarisation_frame is None:
polarisation_frame = PolarisationFrame("stokesI")
npol = polarisation_frame.npol
nchan = len(frequency)
shape = [nchan, npol, npixel, npixel]
w = WCS(naxis=4)
# The negation in the longitude is needed by definition of RA, DEC
w.wcs.cdelt = [
-cellsize * 180.0 / numpy.pi, cellsize * 180.0 / numpy.pi, 1.0,
channel_bandwidth[0]
]
w.wcs.crpix = [npixel // 2 + 1, npixel // 2 + 1, 1.0, 1.0]
w.wcs.ctype = ["RA---SIN", "DEC--SIN", 'STOKES', 'FREQ']
w.wcs.crval = [phasecentre.ra.deg, phasecentre.dec.deg, 1.0, frequency[0]]
w.naxis = 4
w.wcs.radesys = 'ICRS'
w.wcs.equinox = 2000.0
model = create_image_from_array(numpy.zeros(shape),
w,
polarisation_frame=polarisation_frame)
model = insert_skycomponent(model, sc, insert_method=insert_method)
if applybeam:
beam = create_pb(model, telescope='LOW')
model.data[...] *= beam.data[...]
return model
def apply_pb_comp(vt, model, comp):
telescope = vt.configuration.name
pb = create_pb(model, telescope)
return apply_beam_to_skycomponent(comp, pb, flux_limit)
def apply_pb_image(vt, model):
telescope = vt.configuration.name
pb = create_pb(model, telescope)
model.data *= pb.data
return model