Camera stations monitoring the sky and its brightness

Two fisheye cameras take pictures all around the clock at two locations in Germany: one station is located near Münsingen in southern Germany, the other in the Wuhlheide park area of Berlin. The interval is five minutes during daytime and one minute at night. Both cameras are calibrated with Sky Quality Meters (SQMs) to determine the visual brightness of the zenith in each night image.
The images provide additional context for interpreting brightness values, as visible features such as clouds, the moon, the Milky Way, airglow, and sources of light pollution can be seen. The resulting light curves clearly show the dependence of sky brightness on time. These curves are essential for understanding and comparing individual SQM measurements from other locations.