def from_fits_file(cls, fits_file, session,
tilt_equivalency_threshold=0.001,
wavelength_equivalency_threshold=0.0001):
header = fits.getheader(fits_file)
filter1 = GMOSFilter.from_keyword(header['filter1'], session)
filter2 = GMOSFilter.from_keyword(header['filter2'], session)
grating = GMOSGrating.from_keyword(header['grating'], session)
instrument = Instrument.from_keyword(header['instrume'], session)
grating_central_wavelength = header['centwave']
grating_slit_wavelength = header['grwlen']
grating_tilt = header['grtilt']
grating_order = header['grorder']
#Checking if the same instrument setup already exists
instrument_setup_query = session.query(cls).filter(
cls.filter1_id==filter1.id, cls.filter2_id==filter2.id,
cls.grating_id==grating.id, cls.instrument_id==instrument.id,
func.abs(cls.grating_central_wavelength_value -
grating_central_wavelength)
< wavelength_equivalency_threshold,
func.abs(cls.grating_slit_wavelength_value -
grating_slit_wavelength) <
wavelength_equivalency_threshold,
func.abs(cls.grating_tilt_value -
grating_tilt) < tilt_equivalency_threshold)
instrument_setup_object = instrument_setup_query.first()
if instrument_setup_object is None:
instrument_setup_object = cls(
filter1_id=filter1.id,
filter2_id=filter2.id,
grating_id=grating.id,
grating_central_wavelength_value=grating_central_wavelength,
grating_slit_wavelength_value=grating_slit_wavelength,
grating_tilt_value=grating_tilt,
grating_order=grating_order,
instrument_id=instrument.id)
session.add(instrument_setup_object)
session.commit()
return instrument_setup_object
