Notes on Determining Transparency, Seeing, and Limiting Magnitude
I found this scale for transparency and seeing on Deep Sky Observing conditions page. I have not been recording the transparency, seeing, or limiting magnitude with my observation logs, but it is something that I should be doing.
The scales below for transparency and seeing are the ones I will be using for my logs. I am posting the scale here just to make it easy for me to reference, I am also going to include a print out of the scales in each of my log books.
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Seeing (atmospheric stability) and transparency (atmospheric clarity or clearness)
are rated subjectively on 1-10 scales that are based on the guidelines provided by the American Association of Amateur Astronomers.
Seeing is primarily influenced by atmospheric turbulence. The following scale
is used to rate conditions:
1 :: Chaotic: lowest power stellar images unsteady
2-3 :: Severely disturbed: low power planetary/nebulae images unsteady
4-5 :: Poor: medium powers unsteady
6-7 :: Good: only high powers unsteady
8-9 :: Excellent: only highest powers soft
10 :: Superb: all powers steady
Transparency is influenced by cloud cover, relative humidity, and light conditions
which illuminate airborne particulates, including light pollution, moonglow, and
residual sunlight. The following scale is used to rate conditions:
1 :: Mostly Cloudy
2-3 :: Hazy; 1 or 2 Little Dipper stars visible
4 :: 3-4 Little Dipper stars; Milky Way not visible
5 :: 4 Little Dipper stars; Bright parts of Milky Way visible (Scutum starcloud)
6 :: 5 Little Dipper stars; Milky Way visible with averted vision
7 :: 6 Little Dipper stars; Milky Way visible
8-9 :: Excellent: 7 Little Dipper stars; M-31 visible
10 :: Superb: M-33 and/or M-81 visible
Transparency and Seeing page for log book:
Log Book – Seeing and Transparency Scale :: LogBook-SeeingandTransparencyScale.doc
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Here is a nice transparency chart of Ursa Minor (the Little Dipper) from the Society for Popular Astronomy (SPA). Could be useful in helping to determine visual (naked eye) limiting magnitude.
