Clear Sky Chart

Attilla Danko designed all web pages on and wrote all the software that generates clear sky charts.

Allan Rahill designed the numerical forecast models, computed at the Canadian Meteorological Centre(CMC), which feeds the clear sky charts. Neither Allan nor CMC are affiliated with, even though I think they're both pretty cool.

The algorithm which I used to compute the "darkness" line on each clear sky chart is based on Ben Sugarman's algorithm which is an extension of Brad Schaefer's work (1998, Sky & Telescope, Vol. 95, No. 5, p 57).

Light pollution maps are exerpts from the map of North America from the Altas of Artifical Night Sky Brightness. The credit for each light pollution map is:

Credit: 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.

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