Fig. 3From: Imaging of polar cap patches with a low-cost airglow camera: pilot observations in Svalbard, NorwaySummary of the calibration process, a raw image from the WATEC ASI at around 20:35 UT on December 4, 2013, b sensitivity distribution of the WATEC ASI derived from a calibration using integrating sphere, and c absolute optical intensity image of the WATEC ASI at around 20:35 UTBack to article page