SQM night sky brightness measurements at 26 locations in Eastern Austria
I am glad to announce that our recent light pollution paper entitled Systematic measurements of the night sky brightness at 26 locations in Eastern Austria will be soon published in JQSRT. In the article, we show that a correlation between light pollution and air pollution (particular matter) exists. We examine the circalunar periodicity of the night sky brightness, seasonal variations as well as long-term trends. Novel ways to plot and analyze huge long-term SQM (‘Sky Quality Meter’) datasets, such as histograms, circalunar, annual (‘hourglass’) and cumulative (‘jellyfish’) plots are presented (see example below).
Hourglass plots. The x-axis is a time axis, containing the months of one full year. The y-axis is a time axis as well, but covering the hours (and fractions of hours) of the individual nights. A colour scale is used to denote the measured night sky brightness in units of mag arcsec-2 at each time of the night and of the year. The circalunar periodicity or a lack of periodicity can be well recognized in the plots. Also other features emerge, e.g. the natural variation of the night lengths, which creates the ‘hourglass’ shape.
Jellyfish plots. The x-axis is a time axis indicating hours, the y-axis is the night sky brightness in units of mag arcsec-2. These plots show measurements throughout one full year (here: 2016) and the colour indicates the number density of measurements in the (hour, brightness) plane. Here we show urban, light-polluted sites, which are characterized by two clustered regions, that have little to do with the lunar phases, but correspond to clear nights with moderate skyglow on the one hand and overcast nights with strongly enhanced scattering of the city lights.
