Create a PSF cube with FWHM varying along each wavelength plane.
Depending on the value of the ‘fwhm’ parameter, the PSF can be a Gaussian
or a Moffat.
- Parameters:
- fwhm
list List of FHHM values for each wavelength plane.
- beta
float or none if not none, the PSF is a Moffat function with beta value,
else it is a Gaussian.