How many Stars do we still see?

Abstract

We present the results of a nation-wide light pollution awareness and observing campaign, carried out during an Austrian science festival. Data were obtained by issuing a public call via the media and distributing instructions and images of the Little Dipper for 7 different limiting magnitudes 1.5, 2.5 to 6.5. Participants compared the Little Dipper on the sky to the reference images and supplied observing time and location together with an identifier for the image that fitted their observation best. To access the quality of the data we called for observations in an interval containing a significant fraction of the nautical and astronomical twilight. Reports where collected via the web-site: http://www.astro.univie.ac.at/~scw We show the results obtained so far, as an empirical visual limiting magnitude map of Austria and estimate the accuracy by the twilight dependence and a comparison with Walker’s law for the case of Vienna.