Re: Sky Quality Meter - Light Pollution Map Correlation

[Jan Hollan <jhollan@amper....muni.cz>]

Actually, brightness might be defined as another quantity, namely as an
integral of luminance over the space angle. Then, for uniform sky, it
would be 2pi sr times luminance, not just 1 pi sr x luminance = horizontal
illuminance.

Integral of luminance over 2 pi seems to be the quantity Chad and his
team give for those mosaics they take within the Nat. Parks (if their
-7 mag is converted to lm/m2). Unfortunately, they don't give the other
integral (luminance * cos z, over those 2 pi again). But still, the lowest
measured ground illuminance from their data seems to be like 0.7 mlx.
I'm not sure if this was not with some clouds.

so for a slight update...
 jenik