def is_bright_source_near(accessor, distance=20):
"""
Checks if there is any of the bright radio sources defined in targets
near the center of the image.
:param accessor: a TKP accessor
:param distance: maximum allowed distance of a bright source (in degrees)
:returns: False if not bright source is near, description of source if a
bright source is near
"""
#TODO: this function should be split up and tested more atomically
# The measures object is our interface to casacore
m = measures()
# First, you need to set the reference frame -- ie, the time
# -- used for the calculations to come. Time as MJD in seconds.
starttime = int(accessor.taustart_ts.strftime("%s"))
starttime_mjd = unix2julian(starttime)
m.do_frame(m.epoch("UTC", "%ss" % starttime_mjd))
# Now check and ensure the ephemeris in use is actually valid for this
# data.
if not check_for_valid_ephemeris(m):
logger.warn("Bright source check failed due to invalid ephemeris")
return "Invalid ephemeris"
# Second, you need to set your image pointing.
pointing = m.direction(
"J2000", "%sdeg" % accessor.centre_ra, "%sdeg" % accessor.centre_decl
)
for name, position in targets.items():
if not position:
direction = m.direction(name)
else:
direction = m.direction(
"J2000", "%srad" % position['ra'], "%srad" % position['dec']
)
separation = m.separation(pointing, direction).get_value("deg")
if separation < distance:
return "Pointing is %s degrees from %s." % (separation, name)
return False
def is_bright_source_near(accessor, distance=20):
"""
Checks if there is any of the bright radio sources defined in targets
near the center of the image.
:param accessor: a TKP accessor
:param distance: maximum allowed distance of a bright source (in degrees)
:returns: False if not bright source is near, description of source if a
bright source is near
"""
#TODO: this function should be split up and tested more atomically
# The measures object is our interface to casacore
m = measures()
# First, you need to set the reference frame -- ie, the time
# -- used for the calculations to come. Time as MJD in seconds.
starttime = int(accessor.taustart_ts.strftime("%s"))
starttime_mjd = unix2julian(starttime)
m.do_frame(m.epoch("UTC", "%ss" % starttime_mjd))
# Now check and ensure the ephemeris in use is actually valid for this
# data.
if not check_for_valid_ephemeris(m):
logger.warn("Bright source check failed due to invalid ephemeris")
return "Invalid ephemeris"
# Second, you need to set your image pointing.
pointing = m.direction("J2000", "%sdeg" % accessor.centre_ra,
"%sdeg" % accessor.centre_decl)
for name, position in targets.items():
if not position:
direction = m.direction(name)
else:
direction = m.direction("J2000", "%srad" % position['ra'],
"%srad" % position['dec'])
separation = m.separation(pointing, direction).get_value("deg")
if separation < distance:
return "Pointing is %s degrees from %s." % (separation, name)
return False
def test_unix2julian(self):
self.assertEqual(coordinates.unix2julian(0), coordinates.unix_epoch)