I have just finished developing the readers and writers for FITS IRAF format described here. I am going to give a small tutorial on how the specutils package (affiliated with Astropy) can be used for the same, and also give some details of how it works.
To read a FITS file, just simply use specutils.io.read_fits.read_fits_spectrum1d() method. This method might be later moved to Spectrum1D class. The following code snippet gives an example:
from specutils.io import read_fits
spectra = read_fits.read_fits_spectrum1d(example.fits)
Depending on the type of FITS file, the object can be different. For linear or log-linear formats, the object returned will be a Spectrum1D object. For multispec formats, the object will be a list of Spectrum1D objects. The dispersion and the flux of the Spectrum can be accessed using spectrum1Dobject.dispersion and spectrum1Dobject.flux respectively. The dispersion is automatically computed based on the type of dispersion function defined in the header. Other methods such as slicing dispersion for a particular set of flux coordinates will be supported soon.
To write a FITS file, specutils.io.write_fits.write() method. Like the reader, this method may be moved to Spectrum1D later. The following code snippet gives an example:
from specutils.io import write_fits
write_fits.write(spectra, 'example.fits')
The spectra object passed can be a list of Spectrum1D objects or just one Spectrum1D object. Depending on the type of spectra, the writer will write either in multispec or linear format respectively. If the spectra was read in using the reader, then the additional information from the read file will also be written.
There will be some more operations supported, but the focus will be on keeping things simple, and handling the complexities in the code itself.
To read a FITS file, just simply use specutils.io.read_fits.read_fits_spectrum1d() method. This method might be later moved to Spectrum1D class. The following code snippet gives an example:
from specutils.io import read_fits
spectra = read_fits.read_fits_spectrum1d(example.fits)
Depending on the type of FITS file, the object can be different. For linear or log-linear formats, the object returned will be a Spectrum1D object. For multispec formats, the object will be a list of Spectrum1D objects. The dispersion and the flux of the Spectrum can be accessed using spectrum1Dobject.dispersion and spectrum1Dobject.flux respectively. The dispersion is automatically computed based on the type of dispersion function defined in the header. Other methods such as slicing dispersion for a particular set of flux coordinates will be supported soon.
To write a FITS file, specutils.io.write_fits.write() method. Like the reader, this method may be moved to Spectrum1D later. The following code snippet gives an example:
from specutils.io import write_fits
write_fits.write(spectra, 'example.fits')
The spectra object passed can be a list of Spectrum1D objects or just one Spectrum1D object. Depending on the type of spectra, the writer will write either in multispec or linear format respectively. If the spectra was read in using the reader, then the additional information from the read file will also be written.
There will be some more operations supported, but the focus will be on keeping things simple, and handling the complexities in the code itself.
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