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Bussen is an isolated mountain just south of the Swabian Jura and the Danube. It provides a good view over the region Oberschwaben into the southern direction of the alps.
Measurements
The brightness into the zenith direction was down to 21.60 mag/arcsecond² at about 0:40 CET, April 8th, 2026.
This is about 10^(0,4/2,5) = 1.45 times more bright than the usual clear and moonless sky. 1.45 means the sky is brightened by 45 %.
There is no milky way at the night sky of spring in the northern hemisphere. And no airglow was visible, neither by imaging.
21.60 mag/arcsecond² is a good value for southern Germany. As usual in our region, the brightness drops with a slope of about 0.1 mag/arcsecond²
every hour due to decreasing light pollution.
Sources of light pollution
The village Offingen is very close by. However, it shuts down public street lights already at 22:30 CET. This is visible in a considerable drop of
0.06 mag/arcsecond² in the light curve.
The main sources of light pollution are in the direction north-east with Ehingen and its crane company Liebherr (20 km in the distance) and the city
of Ulm with its industrial zone Donautal (about 40 km). In front of Ehingen is Munderkingen (10 km) with bright bluish lights and no sufficient
shielding. East south-east is Biberach in the distance of 18 km.
The region of Stuttgart (74 km) and Reutlingen (45 km) is visible in the northern direction with a broad night glow.
Brightness measurements were obtained every minute in the zenith direction with a SQM-LU-DL, serial number 2030.
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