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Fabry-Perot techniques for observation of diffuse atmospheric sources

An imaging Fabry-Perot interferometer combined with a CCD detector can provide extremely high sensitivity for the detection of diffuse atmospheric spectral emission features. We present a description of the theory and operation of a modern servo-stabilized Fabry-Perot etalon, derive the limiting sensitivity for typical optical configurations, and present astronomical observations of faint, diffuse emission line sources as examples of the technique. We show that sources with intensity as faint as 10-2 Rayleigh can be detected with a few hours of integration.