[alexch (Alex)]

Indeed, in light-pollution free skies, airglow and zodiacal light pose a significant background sky noise problem for professional astronomers.


The fisheye sequence was from the first night and it was free from significant skyglow in the beginning. It was then when I thought "wow, this looks darker than anything I have seen before". It was probably due to low humidity and good transparency too.

However you are absolutely right - it is impossible to compare apples to apples here. For example on those two memorable nights in the observatory on La Palma there was a significant airglow and the sky looked a little milky. In New Zealand it was so strong (following a big geomagnetic storm) that I think I saw the airglow patterns naked eye. I'll try to make a habit of taking circular fisheye images throughout the night at dark sky locations in the future and build up a database. (Do I need another camera?)

Cheers,
Alex