Integrating-sphere calibration of all-sky cameras for nightglow measurements Original Research Article

Three all-sky cooled-CCD cameras designed for mid-latitude nightglow measurements were developed at the Solar-Terrestrial Environment Laboratory and calibrated using a 2-m integrating-sphere and a spectrometer at the National Institute of Polar Research, Japan. Absolute sensitivity and image-flattening data are obtained together with filter transmission functions. We find that filters with highly-flattened image-quality surfaces may cause serious Newtonʹs Ring pattern on final images.