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Re: (meteorobs) RA & Dec
Earl,
I had quite a bit of trouble nailing this down myself, I think I've
got it. The way I went about it was to use a book with detailed maps of the
sky. Polaris is at Dec +90, and all the RA lines converge at this point.
RA 0 goes out right by cassiopia and the eastern part of Pegasus (if memory
serves me correctly) and increases as you "go east" in the sky. Try looking
at a star map while you look at the stars. (by the way, everyone else uses
Hrs & Min, 1 Hr = 15 degrees, 6 Hr = 90, 12 Hr = 180 etc) I started at a
point close to RA 0 degrees, found various landmarks at RA 0,90,180,270,
then went back to my book (converted back to Hr, Min) and found the dec. of
the "landmark" I had chosen. After a short evening of picking out
landmarks (skymarks?), trying to find them in my sky atlas, figuring out
thier Ra & Dec, making a handful of notes on a full sky map, and just
basically playing around with it while actually looking at the stars, I
became somewhat proficient at estimating an objects RA & Dec. It takes a
bit of practice and the only way I would be sure about a "precise" point
would be to go back to the sky atlas, match a point in the sky with a
point in the atlas and convert the exact measurement from one to the other.
I hope that some of this made sense or helped to give you an idea of
how to work with it anyways.
Good Luck,
John Newton
"Cook, Earl" <ecook@AEGONUSA.com> on 08/17/98 02:11:50 PM
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Subject: (meteorobs) RA & Dec
Hi, everyone,
This is really for anyone who is a frustrated Astronomy professor.
I took a basic astronomy course in college, but that was so far
back that a black hole was considered to be one of the caves we
used to explore. Believe me, it's been a looooooong time, and
I have forgotten soooooooo much.
One thing I've always had trouble with it Right Ascension and
Declination. I just came back from an hour at the public library.
I plundered through every book on astronomy they had, and
couldn't find one good explanation of these. I couldn't find
"Astronomy for Real Dummies" either. Even the two books
I checked out (which are tooted as "beginners" or "basic"
books, leave me confused.
OK, one of you "professorial" type guys help me out here.
My location (according to USGS) is Lat 38d,21m; long 85d,54m.
(Forget the "seconds" right now.) Assume I am standing on my
back deck facing north and have a clear view of the Big Dipper
and Polaris. How do I take a position reference, such as:
RA: 14h,14m, Dec: 19d,18m and find it in the sky?
Conversely, if I spot something in the sky and I want to make
reference to it, how do I calculate the RA and Dec (reasonably
close) so I can tell some one else?
I know that for some of you this question is as simple as "how
do I tell when the moon is full?", but try to help me. Please,
keep it simple. My mind ain't as young as it used to be, and
these library books ain't helping any.
RGDS:EARL