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Analogous measurement
(showing but a proxy for horizontal illuminance)
(with almost clear sky up to 23 h, and heavily overcast since about
3:25) from Brno Observatory.
An overview of light condition at this site since June 2006 is at
http://amper.ped.muni.cz/weather.
During this February eclipse, a typical situation of a heavily overcast
sky is apparent in Brno: horizontal illuminance reaches 0.3 lx even without
moonlight... unlike over Tautenburg with much less light pollution.
Before the eclipse, the graph shows the moonlight exaggerated,
this is because of the PV panel having no filter and being sensitive to the
surplus of infrared radiation from the Moon, compared to the Sun
(lunar reflectivity increases quite a lot through red to near infrared).
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