def parse_coordinates(self):
"""Returns a WCS object"""
header = self.header
wcs = WCS()
try:
wcs.crval = header['crval1'], header['crval2']
wcs.crpix = header['crpix1'] - 1, header['crpix2'] - 1
wcs.cdelt = header['cdelt1'], header['cdelt2']
except KeyError:
msg = "Coordinate system not specified in FITS"
logger.error(msg)
raise TypeError(msg)
try:
wcs.ctype = header['ctype1'], header['ctype2']
except KeyError:
wcs.ctype = 'unknown', 'unknown'
try:
wcs.crota = float(header['crota1']), float(header['crota2'])
except KeyError:
wcs.crota = 0., 0.
try:
wcs.cunit = header['cunit1'], header['cunit2']
except KeyError:
# The "Definition of the Flexible Image Transport System", version
# 3.0, tells us that "units for celestial coordinate systems defined
# in this Standard must be degrees", so we assume that if nothing else
# is specifiedj
msg = "WCS units unknown; using degrees"
logger.warning(msg)
wcs.cunit = 'deg', 'deg'
return wcs
def make_wcs(crval=None, cdelt=None, crpix=None):
"""
Make a WCS object for insertion into a synthetic image.
Args:
crval (tuple): Tuple of (RA, Dec) in decimal degrees at the reference
position.
crpix (tuple): Tuple of (x,y) co-ordinates describing the reference
pixel location corresponding to the crval sky-position.
cdelt (tuple): Tuple of (cdelt0, cdelt1) in decimal degrees.
This is the pixel width in degrees of arc, but not necessarily
aligned to RA, Dec unless `crota` is (0,0). If that *is* the case,
then typically cdelt0 is negative since the x-axis is in direction
of West (decreasing RA).
"""
# For any arguments not set we simply assign an arbitrary valid value:
if crval is None:
crval = 100., 45.
if cdelt is None:
pixel_width_arcsec = 40
pixel_width_deg = pixel_width_arcsec / 3600.
cdelt = (-pixel_width_deg, pixel_width_deg)
if crpix is None:
crpix = (256.0, 256.0)
wcs = WCS()
wcs.cdelt = cdelt
wcs.crota = (0.0, 0.0)
wcs.crpix = crpix
wcs.crval = crval
wcs.ctype = ('RA---SIN', 'DEC--SIN')
wcs.cunit = ('deg', 'deg')
return wcs
def setUp(self):
# An image pointing at the north celestial pole
self.ncp_image = DummyImage()
self.ncp_image.wcs = WCS()
self.ncp_image.wcs.cdelt = (-0.009722222222222, 0.009722222222222)
self.ncp_image.wcs.crota = (0.0, 0.0)
self.ncp_image.wcs.crpix = (1025, 1025) # Pixel position of reference
self.ncp_image.wcs.crval = (15.0, 90.0
) # Celestial position of reference
self.ncp_image.wcs.ctype = ('RA---SIN', 'DEC--SIN')
self.ncp_image.wcs.cunit = ('deg', 'deg')
# And an otherwise identical one at the equator
self.equator_image = DummyImage()
self.equator_image.wcs = WCS()
self.equator_image.wcs.cdelt = self.ncp_image.wcs.cdelt
self.equator_image.wcs.crota = self.ncp_image.wcs.crota
self.equator_image.wcs.crpix = self.ncp_image.wcs.crpix
self.equator_image.wcs.crval = (15.0, 0.0
) # Celestial position of reference
self.equator_image.wcs.ctype = self.ncp_image.wcs.ctype
self.equator_image.wcs.cunit = self.ncp_image.wcs.cunit
self.p = get_paramset()
def parse_coordinates(self):
"""Returns a WCS object"""
wcs = WCS()
my_coordinates = self.table.getkeyword('coords')['direction0']
wcs.crval = my_coordinates['crval']
wcs.crpix = my_coordinates['crpix']
wcs.cdelt = my_coordinates['cdelt']
ctype = ['unknown', 'unknown']
# What about other projections?!
if my_coordinates['projection'] == "SIN":
if my_coordinates['axes'][0] == "Right Ascension":
ctype[0] = "RA---SIN"
if my_coordinates['axes'][1] == "Declination":
ctype[1] = "DEC--SIN"
wcs.ctype = tuple(ctype)
# Rotation, units? We better set a default
wcs.crota = (0., 0.)
wcs.cunit = self.table.getkeyword('coords')['direction0']['units']
return wcs
def test_brightsource(self):
wcs = WCS()
wcs.cdelt = (-0.011111111111111112, 0.011111111111111112)
wcs.crota = (0.0, 0.0)
wcs.crpix = (256.0, 256.0)
wcs.crval = (212.83583333333334, 52.2025)
wcs.ctype = ('RA---SIN', 'DEC--SIN')
wcs.cunit = ('deg', 'deg')
image = MockImage(
{
"url": "dummy",
"tau_time": 58141509,
"taustart_ts": datetime.datetime(2012, 4, 6, 3, 42, 1),
"centre_ra": 212.83583333333334,
"centre_decl": 52.2025,
"freq_eff": 128613281.25,
"freq_bw": 1940917.96875,
"beam":
(1.9211971282958984, 1.7578132629394532, 1.503223674140207)
}, wcs)
# this image is not near any bright sources
result = tkp.quality.brightsource.is_bright_source_near(image)
self.assertFalse(result)
# there is nothing bright here
image.centre_ra = 90
image.centre_decl = 0
result = tkp.quality.brightsource.is_bright_source_near(image)
self.assertFalse(result)
# this is near the sun
image.centre_ra = 0
image.centre_decl = 0
result = tkp.quality.brightsource.is_bright_source_near(image)
self.assertTrue(result)
# this is near CasA
image._centre_ra = degrees(6.123487680622104)
image._centre_decl = degrees(1.0265153995604648)
result = tkp.quality.brightsource.is_bright_source_near(image)
self.assertTrue(result)
