[AZ-Observing] Re: Estimating size and brightness
- From: "Thad Robosson" <starstarcracker@xxxxxxxxx>
- To: az-observing@xxxxxxxxxxxxx
- Date: Thu, 29 Jan 2004 07:39:56 -0700
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.
Just my 0.533416 Czech Republic Koruny worth.
Thad
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