We report on luminance measurements of the summer night sky at a field site
on a freshwater lake in northeastern Germany (Lake Stechlin) to evaluate the
amount of artificial skyglow from nearby and distant towns in the context of a
planned study on light pollution. The site is located about 70 km north of
Berlin in a rural area possibly belonging to one of the darkest regions in
Germany. Continuous monitoring of the zenith sky luminance between June and
September 2015 was conducted utilizing a Sky Quality Meter. With this device,
typical values for clear nights in the range of 21.5-21.7
magSQM/arcsec2 were measured, which is on the order of the natural sky
brightness during starry nights. On overcast nights, values down to 22.84
magSQM/arcsec2 were obtained, which is about one third as bright as on
clear nights. The luminance measured on clear nights as well as the darkening
with the presence of clouds indicate that there is very little influence of
artificial skyglow on the zenith sky brightness at this location. Furthermore,
fish-eye lens sky imaging luminance photometry was performed with a digital
single-lens reflex camera on a clear night in the absence of moonlight. The
photographs unravel several distant towns as possible sources of light
pollution on the horizon. However, the low level of artificial skyglow makes
the field site at Lake Stechlin an excellent location to study the effects of
skyglow on a lake ecosystem in a controlled fashion.Comment: 20 pages, 8 figures, Journal of Quantitative Spectroscopy and
Radiative Transfer 201
