Versatile family of modular aurora and airglow photometers.

A photometer system has been designed that incorporates the concepts of modularity and fully digitized control and data recording electronics. Modularity allows field substitution of background subtraction techniques, filter choice, and choice of input optical configuration. Novel features include a trichroic filtering module that allows simultaneous monitoring of auroral or airglow emission intensities in three spectral regions with the same field of view and input optics. Also described is a novel three-beam adaptation that allows monitoring of the emission intensity from three closely spaced regions in the upper atmosphere in the same spectral region. The digital counting and control electronics described are compatible with NIMBIN plug-in modules and allow expansion of the system to many photon-counting channels as well as ready interfacing with other data sources.