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Re: matching coordinates [message #55066 is a reply to message #55065]

Mon, 30 July 2007 03:36

jradavenport
Messages: 6
Registered: July 2007

Junior Member

On Jul 29, 7:53 am, David Fanning <n...@dfanning.com> wrote:
> jradavenp...@gmail.com writes:
>> Hello, I'm a long time lurker of this group, and finally have a
>> problem I can't solve efficiently enough! I have coordinates for stars
>> (RA and DEC for us astronomers out there), from two sources. i.e.
>> (x1,y1) and (x2,y2). These lists are huge, like 150k for one and
>> 5million in the other (a lot of stars!). I need to find the matches
>> from these catalogs within a tolerance. I've tried a few programs
>> I've found online (close_match_radec for instance) and they have not
>> given me results I believe (multiple matches and such). Here is some
>> horrible code I wrote just now which solves the problem VERY slowly:
>
> Here is an article that might help:
>
> http://www.dfanning.com/code_tips/matchlists.html
>
> For background, you might want to read the precursor
> article, and one of my personal favorites:
>
> http://www.dfanning.com/code_tips/slowloops.html
>
> Cheers,
>
> David
> --
> David Fanning, Ph.D.
> Fanning Software Consulting, Inc.
> Coyote's Guide to IDL Programming:http://www.dfanning.com/
> Sepore ma de ni thui. ("Perhaps thou speakest truth.")

Thanks David, Big fan of your site and of yours and JD Smith's code...
I guess it really is time to learn that Histogram function (something
I've put off for over a year!)

I'm turning that example code into a workable program, but am confused
on where the results are. Which Variable do I want to return with the
answers?

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[Message index]

		Re: matching coordinates By: JD Smith on Mon, 30 July 2007 17:20
		Re: matching coordinates By: Conor on Mon, 30 July 2007 07:58
		Re: matching coordinates By: jradavenport on Mon, 30 July 2007 04:12
		Re: matching coordinates By: jradavenport on Mon, 30 July 2007 03:36
		Re: matching coordinates By: Anthony[1] on Mon, 30 July 2007 00:41
		Re: matching coordinates By: Anthony[1] on Mon, 30 July 2007 00:41
		Re: matching coordinates By: David Fanning on Sun, 29 July 2007 06:53

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