A system of medium resolution for monitoring the night sky background in the visible and near UV range

In this work we focus on a design of a medium resolution spectrograph for the night sky background radiation, in conjunction with appropriate telescopes, in order to seek for the optimum performance. Best results seem to be obtained using concave gratings. Using a grating with about 800 grooves per mm designed for flat field spectrograph and 24 cm focal length, we are able to record night sky background spectra in a reasonably small time interval while the light detector used is based on a commercial dSLR camera. The spectra obtained show the expected line from atomic oxygen nightglow at 557.7 nm, and the pseudo-continuum part is consistent with data from telescope-based spectrometers. This instrumentation may become a versatile tool for diagnostics in Extensive Air Shower fluorescence telescopes development and operation.