Should specutils support logarithmic spectral axes?

[aragilar]

Using/storing spectra with logarithmic wavelength is not uncommon, should specutils support this, and if so, how should it work?

Currently someone can set spectral_axis to an array where the difference between the values is logarithmic, or try to encode the details into WCS, but then either the user must reconvert the values back to log-scale, or the resulting Spectrum1D.spectral_axis is generated by exponentiating the values. It would be nice if logarithmic scales could be stored and used where needed, and conversions only happen when required.