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Dear all,
I would like to take calibrated spectra of light polution background of my observing site. Of course it is very conspicuous and it is present in every long exposure time spectrum, but ¿how I could calibrate it in wavelength, in absence of the hydrogen Balmer lines?

This would be useful to me to check my spectra and to be sure there is no intrusion of light pollution emission lines.

Hi Miguel,

I've played around with background spectra when tried to use it for calibration.

One that you could do easily is processing any fainter target A-star spectra with AND without 'Sky not removed" checkbox at ISIS 2. General tab, then just subtract one from the other (ISIS Tools, one of spectra basic operations).
Alternatively, you can also do a very long background recording, then take a simple very bright A star, then in ISIS Tools tab just add the 2 raw .fit files (eventually multiplying one of them if other is too bright) to produce an artifically polluted star, then switch on/off 'Sky not removed' + subtract results. I was able to produce such articial polluted spectra very easily.

Identification is the next issue, I was only able to google around and guess the components.

HTH

Thans very much Peter, this is very helpful.