We extend the method introduced by Cinzano et al. (2000a) to map the
artificial sky brightness in large territories from DMSP satellite data, in
order to map the naked eye star visibility and telescopic limiting magnitudes.
For these purposes we take into account the altitude of each land area from
GTOPO30 world elevation data, the natural sky brightness in the chosen sky
direction, based on Garstang modelling, the eye capability with naked eye or a
telescope, based on the Schaefer (1990) and Garstang (2000b) approach, and the
stellar extinction in the visual photometric band. For near zenith sky
directions we also take into account screening by terrain elevation. Maps of
naked eye star visibility and telescopic limiting magnitudes are useful to
quantify the capability of the population to perceive our Universe, to evaluate
the future evolution, to make cross correlations with statistical parameters
and to recognize areas where astronomical observations or popularisation can
still acceptably be made. We present, as an application, maps of naked eye star
visibility and total sky brightness in V band in Europe at the zenith with a
resolution of approximately 1 km.Comment: 15 pages, 8 size-reduced PostScript figures, accepted for publication
in Monthly Notices of the Royal Astronomical Society, high-resolution
original maps will be available as zipped TIFF files from
http://www.pd.astro.it/cinzano/page93.htm