Remove `wcs1d_multispec` reader.

@dr-rodriguez がすでに取り組んでいます。

2025年11月11日 から。

Specutils *should* be able to handle this. Not sure if it's already been implemented in specutils or not but we should try to remove this from the AstrodbKit code base.

This is the test file:
`filename = "https://s3.amazonaws.com/bdnyc/optical_spectra/U10929.fits"`

```Python
def identify_wcs1d_multispec(origin, *args, **kwargs):
"""
Identifier for WCS1D multispec
"""
hdu = kwargs.get("hdu", 0)

# Check if number of axes is one and dimension of WCS is greater than one
with read_fileobj_or_hdulist(*args, **kwargs) as hdulist:
return (
hdulist[hdu].header.get("WCSDIM", 1) > 1
and hdulist[hdu].header["NAXIS"] > 1
and "WAT0_001" in hdulist[hdu].header
and hdulist[hdu].header.get("WCSDIM", 1) == hdulist[hdu].header["NAXIS"]
and "LINEAR" in hdulist[hdu].header.get("CTYPE1", "")
)

@data_loader("wcs1d-multispec", identifier=identify_wcs1d_multispec, extensions=["fits"], dtype=Spectrum, priority=10)
def wcs1d_multispec_loader(file_obj, flux_unit=None, hdu=0, verbose=False, **kwargs):
"""
Loader for multiextension spectra as wcs1d. Adapted from wcs1d_fits_loader

Parameters
----------
file_obj : str, file-like or HDUList
FITS file name, object (provided from name by Astropy I/O Registry),
or HDUList (as resulting from astropy.io.fits.open()).
flux_unit : :class:`~astropy.units.Unit` or str, optional
Units of the flux for this spectrum. If not given (or None), the unit
will be inferred from the BUNIT keyword in the header. Note that this
unit will attempt to convert from BUNIT if BUNIT is present.
hdu : int
The index of the HDU to load into this spectrum.
verbose : bool
Print extra info.
**kwargs
Extra keywords for :func:`~specutils.io.parsing_utils.read_fileobj_or_hdulist`.

Returns
-------
:class:`~specutils.Spectrum`
"""

with read_fileobj_or_hdulist(file_obj, **kwargs) as hdulist:
header = hdulist[hdu].header
wcs = WCS(header)

# Load data, convert units if BUNIT and flux_unit is provided and not the same
if "BUNIT" in header:
data = u.Quantity(hdulist[hdu].data, unit=header["BUNIT"])
if u.A in data.unit.bases:
data = data * u.A / u.AA # convert ampere to Angroms
if flux_unit is not None:
data = data.to(flux_unit)
else:
data = u.Quantity(hdulist[hdu].data, unit=flux_unit)

if 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
wcs.unit = tuple(wcs.wcs.cunit)

# Identify the correct parts of the data to store
if len(data.shape) > 1:
flux_data = data[0]
else:
flux_data = data
uncertainty = None
if "NAXIS3" in header:
for i in range(header["NAXIS3"]):
if "spectrum" in header.get(f"BANDID{i+1}", ""):
flux_data = data[i]
if "sigma" in header.get(f"BANDID{i+1}", ""):
uncertainty = data[i]

# Reshape arrays if needed
if len(flux_data) == 1 and len(flux_data.shape) > 1:
flux_data = np.reshape(flux_data, -1)
if uncertainty is not None:
uncertainty = np.reshape(uncertainty, -1)

# Convert uncertainty to StdDevUncertainty array
if uncertainty is not None:
uncertainty = StdDevUncertainty(uncertainty)

# Manually generate spectral axis
pixels = [[i] + [0] * (wcs.naxis - 1) for i in range(wcs.pixel_shape[0])]
spectral_axis = [i[0] for i in wcs.all_pix2world(pixels, 0)] * wcs.wcs.cunit[0]

# Store header as metadata information
meta = {"header": header}

return Spectrum(flux=flux_data, spectral_axis=spectral_axis, uncertainty=uncertainty, meta=meta)
```