[AZ-Observing] Re: Estimating size and brightness
- From: "Stanley A. Gorodenski" <stan_gorodenski@xxxxxxxxxxxxx>
- To: az-observing@xxxxxxxxxxxxx
- Date: Thu, 29 Jan 2004 08:42:26 -0800
Thad,
Maybe you could submit this technique as a note in an appropriate
publication. It seems to me worthwhile.
Stan
Thad Robosson wrote:
>Hey All,
>Forgive me if I've already said some of this in an earlier thread, but it's
>pertinent again. Anyway,
>Brightness is obviously going to be subjective unless there's some ready
>comparison at hand, but size
>can be relatively accurate with a few items. Here's what I do.....First,
>determine the FOV for your various EP's.
>Then, set up some sort of drawing form, or at least a circle of an easy
>diameter, say 3". From there, you can determine what some arbitrary distance,
>say 30', appears like in a 3" circle. ie...given a 2* FOV and a 3" circle, a
>line 30' long is 3/4 an inch long in the circle. You could set up
>transparency with various length lines on it to slide over your circle to help
>determine various angular measures for your EP's. I took this a step further
>by milling some notches in aluminum sheets so I could draw a distance line
>right into my sketches, a'la Skiff & Linganbuhl (sp?). You don't necessarily
>need to sketch, just the printed circle with a transparency would be a big
>help in judging angular size.
>
>Another aspect I've "helped" myself with is ratio as in comes to play with
>galaxies. I used a CAD program to print up ellipses of various ratios, 2:1,
>3:1, 4:1, etc. That really helps my descriptions along and makes this
>judgement quite a bit easier.
>
>
>
>
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