Shouldn’t it possible to extract useful information from the sky background in the photometrically calibrated images and spectra we take ? If so there could already be a huge (untapped ?) historical source of data covering a range of passbands, locations, air mass and atmospheric conditions
Cheers
Robin
That is a damned good idea! I alone have over 30,000 images neatly catalogued, most of which contain little but stellar images so determining the background sky brightness should be possible.
The FITS headers of mine not only have RA, Dec and time recorded, they also have altitude and azimuth (admittedly easily computed from the first three) so more than just air mass is available – the distribution over the sky, such as city lights, can also be determined. About the only thing I don’t have recorded is the weather condition at the time of exposure but perhaps there are other public records of that too.