Wednesday, August 25, 2010


And now for something totally different that no one who reads it will possibly care about =) (That is, keeping with tradition...)

The age-old debate among amateur astronomers: to log or not to log, and in what detail? I say, log, sketch, describe, and record details about conditions and equipment, but don't bother with the object details that are easily looked up in any database. I write down time, date, location, seeing, transparency, equipment used, description, and sketch (in a circle traced from an altoids tin lid). Not too cumbersome but more than adequate.

And, don't bother with the specially marketed logging notebooks. They will never be exactly right for your preferences and aren't flexible enough for the many situations you encounter. I use very small circles for multiple stars, bigger for standard deep sky objects, bigger yet for huge and detailed open and globular clusters, and lots of circles mashed together when several interesting things are within a field of view or two from each other. Some descriptions are very short, others very long. I don't keep a list of transparency test stars (and find it incredibly tedious to accurately measure transparency, so I guess and round...), but I do have a list of eyepiece specs, Messier observation page numbers, etc. And I like to write down details about the trip and people and events in a diarylike fashion, right with the deep space observations. It's just easier to use a standard quadrille notebook and mold it to my purposes.

What's the purpose of all that work? At least tenfold:

  1. Logging objects lets you keep track of what you've seen in what conditions, so you don't fall into the trap of looking at the same dozen objects every time just because you like them and don't want to look up new things. Or you forgot you've already seen it. Easy to do with names like "IC1322".
  2. Drawing forces you to notice details that you would otherwise never see, and remember them. Without that detail, every object is just another grey smudge after you've seen the first dozen.
  3. Drawing forces you to improve your observational skills since you can compare your drawings to photographs and others' drawings for accuracy and things missed.
  4. Logging forces you to learn more of the scientific context, since to describe accurately you need to know what it is and how far it is and technical details like magnitude, degree of separation, etc. It's more satisfying to say "rich starforming region ~10 arcminutes across but obscured by dust cloud" than "brighter fuzzy patch next to a sort of darkish area".
  5. Describing objects forces you to notice more detail and also to mentally compare each object to the others you've seen, which gives you a growing context of understanding. You can't say "smallish cluster with a bright core" without knowing what is average size and average core brightness.
  6. Logbooks are incredibly fun to re-read over the years. It's stunning the level of crappiness of my earliest observations. And since I recorded all the details about my first star parties and astronomy camp etc etc, I'll always be able to relive those things.
  7. You will always have a reference when you can't remember what that cool green planetary nebula was or who gave a talk on galaxy clusters. It's like a research logbook in that way, which I also keep in a detailed manner (formerly in a notebook, now in the form of every version of every file and tons and tons of notes in text files and annotated pdfs...)
  8. You can use these logs to acquire Astronomical League observing club pins, since they require proof of every observation. It would be silly to start from scratch if you've already seen many of the objects.
  9. You can confirm your observations of very difficult objects by comparing your drawing to the digital sky survey. Lingering doubt makes it not very satisfying to say "I saw NGC4565" when you really mean "I think I kind of saw something in that area when I averted my eyes and jiggled the scope, maybe..."
  10. It's fun!

The downside to logging in this level of detail, of course, is that it takes a long time and is potentially very tedious (as when drawing a dense resolvable open cluster... try drawing 300 precisely-placed dots in a circle sometime...) I can observe every Messier object in a single night in March, but I'm still working on drawing them all. But it's definitely worth it! The longer it's been since I logged something, the happier I am that I did. Exponential returns!

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