3 comments on “NELM and SQM in late March in Sodankylä, Finland

  1. I curious how you are estimating NELM as your numbers seems to be a bit higher than what the SQM numbers suggest. For example a NELM of 5.5 is around 20 on the SQM (mags per arcsec squared). Most people who estimate NELM visually (Ursa Minor W-Umi technique) usually underestimate rather than overestimate due to their eyes being not dark adapted enough.Clear Skies, Colin (another geoscientist – actually geophysicist).

  2. Hi, and thanks for your comment! In this project I estimated NELM just by taking a random area of the sky that is at least of altitude 50 and that is free of light pollution. Then I just sketched the stars that I could see, and then I checked afterwards from Sky Map Pro, which was the faintest star that I was able to see. Nowadays I'm still using the same technique but now I mostly use Ursa Minor as the constellation where I draw the stars I can see.

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