GLOBE at Night Results for 2011
The total number of measurements during the 2011 GLOBE at night campaign was 14,249. The largest number of countries (115) participated in this year’s event; 48 of those countries contributed nearly 99% of all measurements. The top dozen contributing countries accounted for 85% of all GLOBE at Night measurements in 2011. Nearly half of all the measurements were from the United States (49 states plus the District of Columbia). 10% of all measurements (or 1400 measurements) were from Arizona. The country with the next largest contribution of measurements was Poland (with over 1200). India came in third with over 700 measurements. The other countries in the top dozen were South Korea, Croatia, Puerto Rico, the Czech Republic, Chile, Germany, Colombia, Canada and Japan (with measurements between 300 and 450).
Every 3 out of 5 measurements of limiting magnitude gave a value of 3 or 4 mag, which is typical of measurements contributed by medium to larger sized cities. 82% of the measurements (or slightly more than every 4 out of 5 measurements) were taken in light polluted areas and less than 18% (less than every 1 out of 5 measurements) from areas where you could see the Milky Way Galaxy. (The numbers are consistent with what the International Dark-Sky Association finds for the United States.)
For full access to the GLOBE at Night data base, data files in various formats from any of the 6 years are downloadable from the map page. Additionally, clicking any map on that page will open a second window with an interactive world map on which you can display data from any year, limiting magnitude, and topological appearance. And you can zoom in to within a few kilometers resolution.