Model map of the night sky glow in the mountain areas in Poland with the marked values of Sa obtained by the SQM in the period 2008-2012
Marked boundaries of Polish, Czech and Slovak national parks
[Credit: Ściężor T. Light pollution of the night sky in Cracow Agglomeration. Data analysis of the artificial sky glow measurements (in Polish), Kraków 2010, on the base of the map: P. Cinzano, F. Falchi (University of Padova), C. D. Elvidge (NOAA National Geophysical Data Center, Boulder). Copyright Royal Astronomical Society. Reproduced from the Monthly Notices of the RAS by permission of Blackwell Science.]