Quote:
Originally Posted by strongmanmike
So with the narrower sensing L model, is it a good idea to point it away from the Milky Way in general..or just accept that the readings will vary overhead throughout the year?
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Yes definitely Mike. Point it away from the Milky Way and preferably to get the most relatable readings point it at the zenith when the milky way is nowhere near the zenith. It all relates to the concept of the SQM meter being to measure the underlying or background Sky brightness, away from the moon and other sources like the Milky Way and other large sources or city light domes. That is then the best way to compare Site A with Site B.
If for instance Site A was a REALLY DARK site, but an SQM measurement was taken with the moon up, the milky way core at zenith, a few clouds scattering the moonlight, etc.. then it might not appear that dark,
from an SQM reading point of view, compared with perhaps a Site B a modestly dark site, but with an SQM reading taken at the zenith, on a clear night, with no moon and with the Milky Way at the horizon.
It's all about trying to measure the background sky brightness under similar conditions so that different sites or even nights can be compared.
Only one thing to consider is if near a city with a VERY large light dome, the zenith may not always be the darkest patch of sky. In that case I suppose I'd measure off to the side a little. This is sometimes seen when a city borders the sea or in some rural settings near a large city.
Best
JA