Hi Dennis & All,
Quote:
Originally Posted by Dennis
PS – ZLM I guess is Zenith Limiting Magnitude, but what is the “L” in Sky Quality Meter – L?
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Yep, ZLM is Zenithal Limiting Magnitude -- this seems nowadays to be falling into dissetude and most observers write NELM (Naked Eye Limiting Magnitude) -- they mean the same thing, but ZLM was the term when I was a boy so ...
One I'm surprised no one has asked about (picked me up on) is my use of "eg" for galaxy. This is nowadays a quite rare contraction. It is short for Extra Galactic Nebulae. The galaxies, were originally known as exta galactic nebulae before the term galaxy took over. I guess I could use gx, but I am old-fashioned and well, I just like "eg".
SQM-L is the model of the SQM that has a lens in front of the sensor restricting the FOV to about 20 deg FWHM. Tends to cut out the "milky way effect" the lense-less SQM (that view a much wider angle) suffer from.
Best,
Les D