Observing report key

Most things on in my observing reports are self-explanatory if you are an amateur astronomer.

A few abbreviations

Seeing/Visibility

While I often give more detailed information in the body of the report, I give a standardized assessment of sky conditions at the top of the report. I'm generally not very concerned with seeing; I'm more of a "faint fuzzy" type of observer. So, unless I'm observing a planet or decide to go for a double star or two, I don't say much about seeing. Plus, my old observations are made with apertures of 60mm or less, for which seeing of 2 arc seconds is still "perfect".

I'm much more concerned with how faint of objects can be seen. This is usually called "transparency". However, many people restrict this term to conditions in the atmosphere such as fog, haze, clouds, etc., and not to the loss of faint object due to light pollution. All I care about is the overall impression and not whether the problem is light pollution, or atmospheric phenomena, or a combination. In any case, light pollution is already an atmospheric phenomenon and varies strongly depending on the quantity of water vapor, aerosols, etc. in the air. Thus, I'm going to use the term "visibility" to roughly indicate how faint of objects I can see, both stars and "faint fuzzies". The text of the report will indicate whether there is haze, light pollution, etc., and whether I made a detailed check of my NLM. The analogy is to weather reports, where visibility is simply how far an observer can see objects, while other parts of the weather record will indicate exactly what is causing a visibility restriction.

My grading system for visibility is influenced in part by thoughts on the subject from veteran observer John Bortle and follow a similar magnitude breakdown. I'm not sure how useful it will be for someone else, but I've also chosen diffuse objects that are visible relatively high in the sky for most Northern Hemisphere observers. When I have determined a more precise NLM, I also quote that number.


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