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Questions about annual aberration and annual parallax of stars



 
 
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  #1  
Old August 8th 06, 06:21 AM posted to sci.astro
subhash
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Posts: 9
Default Questions about annual aberration and annual parallax of stars

Dear Members,
Please help me to reply the following -
The measurement of the major axis of the ellipses formed by stellar
aberration and parallax by taking the positional photographs in the
observatories of the star under consideration time to time in the
duration one year then the major axis are majored of both the ellipses
given the value of stellar aberration and parallax respectively. The
value of the major axis of aberrational ellipse is 20.47 as a constant
for all the stars while the value of the parallax ellipse changes star
to star. The maximum value being .772 arc-second for the nearest star
Proxima Cen while this value is different for other distant stars. The
distances of the stars is calculated as 1/parallax arc-second.
Now my problem is the value of major axis for the aberrational ellipse
is perfectly constant 20.47 for each star(it is true mathematically but
I want to know experimentally) or it varies by slight values if it
varies then what is the lower and upper limit of variation.
I will be much oblidged for the reply or the suggestion that where can
I get the proper detailed answer.
With deep regards,

S.C. Jain
e-mail

  #2  
Old August 8th 06, 06:20 PM posted to sci.astro
Steve Willner
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Posts: 1,172
Default Questions about annual aberration and annual parallax of stars

In article .com,
"subhash" writes:
The
value of the major axis of aberrational ellipse is 20.47 as a constant


That's the value at the ecliptic pole. For other positions, you get
a projection of this ellipse.

I expect any textbook on astrometry will cover both aberration and
parallax in detail. I tried searching "astrometry" and "positional
astronomy" at Amazon and got some hits, but it wasn't easy to tell
which books are any good, and a lot of them are expensive.

Your best bet might be to browse through a university library. Jean
Meeus has written several books on practical calculations, but I
don't know which if any of them covers precession and aberration in
detail. Our library owns _Modern Astrometry_ by Jean Kovalevsky;
maybe you could get it on interlibrary loan. Or maybe other posters
here will have better recommendations. You might try the link at the
bottom of this message, though I don't guarantee it will work.

http://www.amazon.com/gp/product/sit...0?ie=UTF8#bort

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Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA
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