I’ll have a try at extracting it from the background. I don’t understand where all the emission lines in the sky background come from though. They do not look like galactic lines to me. Do they have an unusual light pollution problem or something or perhaps they superimpose the calibration lamp spectrum?
EDIT: ok the “emission lines” are actually severe fringing in the IR. I can see the O2 telluric band so should be able to cross check the wavelength calibration.