Skip to content

Address wcs1d loader failures on various IRAF multispec formats #1127

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Draft
wants to merge 1 commit into
base: main
Choose a base branch
from
Draft

Address wcs1d loader failures on various IRAF multispec formats #1127

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
47 changes: 30 additions & 17 deletions specutils/io/default_loaders/wcs_fits.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -125,7 +125,6 @@ def wcs1d_fits_loader(file_obj, spectral_axis_unit=None, flux_unit=None,
raise ValueError('No HDU with spectral data found.')

header = hdulist[hdu].header
wcs = WCS(header)

if 'BUNIT' in header:
data = u.Quantity(hdulist[hdu].data, unit=header['BUNIT'])
Expand Down Expand Up @@ -188,23 +187,37 @@ def wcs1d_fits_loader(file_obj, spectral_axis_unit=None, flux_unit=None,
uunit = uunit**UNCERT_EXP[unc_type.lower()]
uncertainty = UNCERT_REF[unc_type](u.Quantity(uncertainty, unit=uunit))

# Have to translate to WCS-recognised keywords for IRAF-Multispec format:
if header.get('CTYPE1', 'WAVE') == 'MULTISPE':
header['SYSTEM'] = 'MULTISPE'
if 'WAT1_001' in header:
# Try to extract from IRAF-style card or use Angstrom as default.
wat_dict = dict((rec.split('=') for rec in header['WAT1_001'].split()))
unit = wat_dict.get('units', 'Angstrom')
if hasattr(u, unit):
header['CUNIT1'] = unit
else: # try with unit name stripped of excess plural 's'...
header['CUNIT1'] = unit.rstrip('s')
ctype_def = u.Unit(header['CUNIT1']).physical_type
ctype_def = 'WAVE' if 'length' in ctype_def else list(ctype_def)[0]
ctype1 = wat_dict.get('label', ctype_def)
header['CTYPE1'] = ctype1[:4].upper()
if verbose:
print(f"Extracted spectral axis '{header['CTYPE1']}' "
f"with unit '{header['CUNIT1']}' from 'WAT1_001'")
elif header.get('CUNIT1', '') == '':
header['CUNIT1'] = 'Angstrom'
header['CTYPE1'] = 'WAVE'

wcs = WCS(header)
if spectral_axis_unit is not None:
wcs.wcs.cunit[0] = str(spectral_axis_unit)
elif wcs.wcs.cunit[0] == '' and 'WAT1_001' in header:
# Try to extract from IRAF-style card or use Angstrom as default.
wat_dict = dict((rec.split('=') for rec in header['WAT1_001'].split()))
unit = wat_dict.get('units', 'Angstrom')
if hasattr(u, unit):
wcs.wcs.cunit[0] = unit
else: # try with unit name stripped of excess plural 's'...
wcs.wcs.cunit[0] = unit.rstrip('s')
if verbose:
print(f"Extracted spectral axis unit '{unit}' from 'WAT1_001'")
elif wcs.wcs.cunit[0] == '':
wcs.wcs.cunit[0] = 'Angstrom'

# Compatibility attribute for lookup_table (gwcs) WCS
# Compatibility attribute for lookup_table (gwcs) WCS; set physical_type for Spectrum1D.
wcs.unit = tuple(wcs.wcs.cunit)
if verbose:
print(f"WCS spectral axis unit '{wcs.unit}'")
print(f"WCS physical axes '{wcs.world_axis_physical_types}'")

meta = {'header': header}

Expand Down Expand Up @@ -535,12 +548,12 @@ def _read_non_linear_iraf_fits(file_obj, spectral_axis_unit=None, flux_unit=None
wat_dict = dict((rec.split('=') for rec in header['WAT1_001'].split()))
unit = wat_dict.get('units', 'Angstrom')
if hasattr(u, unit):
spectral_axis_unit = unit
spectral_axis_unit = u.Unit(unit)
else: # try with unit name stripped of excess plural 's'...
spectral_axis_unit = unit.rstrip('s')
spectral_axis_unit = u.Unit(unit.rstrip('s'))
if verbose:
print(f"Extracted spectral axis unit '{spectral_axis_unit}' from 'WAT1_001'")
spectral_axis *= u.Unit(spectral_axis_unit)
spectral_axis *= spectral_axis_unit

return spectral_axis, data, dict(header=header)

Expand Down