import logging
import astropy.units as u
from astropy.coordinates import SkyCoord
from banzai.stages import Stage
from banzai.utils import qc
logger = logging.getLogger('banzai')
class PointingTest(Stage):
"""
A test to determine whether or not the poiting error on the frame
(as determined by a WCS solve) is within tolerance.
"""
# Typical pointing is within 5" of requested pointing (decimal degrees).
WARNING_THRESHOLD = 30.0
SEVERE_THRESHOLD = 300.0
def __init__(self, runtime_context):
super(PointingTest, self).__init__(runtime_context)
def do_stage(self, image):
try:
# OFST-RA/DEC is the same as CAT-RA/DEC but includes user requested offset
requested_coords = SkyCoord(image.meta['OFST-RA'], image.meta['OFST-DEC'],
unit=(u.hour, u.deg), frame='icrs')
except ValueError as e:
try:
# Fallback to CAT-RA and CAT-DEC
requested_coords = SkyCoord(image.meta['CAT-RA'], image.meta['CAT-DEC'],
unit=(u.hour, u.deg), frame='icrs')
except:
logger.error(e, image=image)
return image
# This only works assuming CRPIX is at the center of the image
solved_coords = SkyCoord(image.meta['CRVAL1'], image.meta['CRVAL2'],
unit=(u.deg, u.deg), frame='icrs')
angular_separation = solved_coords.separation(requested_coords).arcsec
logging_tags = {'PNTOFST': angular_separation}
pointing_severe = abs(angular_separation) > self.SEVERE_THRESHOLD
pointing_warning = abs(angular_separation) > self.WARNING_THRESHOLD
if pointing_severe:
logger.error('Pointing offset exceeds threshold', image=image, extra_tags=logging_tags)
elif pointing_warning:
logger.warning('Pointing offset exceeds threshhold', image=image, extra_tags=logging_tags)
qc_results = {'pointing.failed': pointing_severe,
'pointing.failed_threshold': self.SEVERE_THRESHOLD,
'pointing.warning': pointing_warning,
'pointing.warning_threshold': self.WARNING_THRESHOLD,
'pointing.offset': angular_separation}
qc.save_qc_results(self.runtime_context, qc_results, image)
image.meta['PNTOFST'] = (angular_separation, '[arcsec] offset of requested and solved center')
return image
