SKY SPECTRA AT A LIGHT-POLLUTED SITE AND THE USE OF ATOMIC AND OH SKY EMISSION-LINES FOR WAVELENGTH CALIBRATION

Spectra of the night sky, taken at Lick Observatory in 1988 and 1989 as byproducts of nebular spectra, show the great increase of light pollution by sodium high- and low-pressure lamps in comparison with previous spectra taken in 1975. The usefulness of the emission lines of the night sky spectrum for wavelength calibration is mentioned. In the far-red and near-infrared regions, where there are only few atomic night-sky lines, the OH vibration-rotation spectrum may be used for this purpose. Accurate rest wavelengths for these lines, calculated from the best laboratory determinations, are tabulated, and the special suitability of the P1 (and to a lesser extent P2) lines is discussed.