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Re: circles on the sky [message #65935 is a reply to message #65879]

Tue, 31 March 2009 14:20

pgrigis
Messages: 436
Registered: September 2007

Senior Member

Christopher Thom wrote:
> Quoth Kenneth P. Bowman:
>
>> In article <alpine.OSX.1.10.0903311335490.8491@kanangra.uchicago.edu>,
>> Christopher Thom <cthom@oddjob.uchicago.edu> wrote:
>>
>>> Given a co-ordinate position (ra/dec or lat/long), a direction (e.g an
>>> angle east of north, for instance), and a great circle angular distance,
>>> how do I compute the coordinate of the final position?
>>
>> LL_ARC_DISTANCE.
>>
>> What! That wasn't obvious? :-)
>>
>> (This function should be referenced in the manual page for MAP_2POINTS,
>> and vice versa.)
>
> AHA!!! Missed this one. Now, by just passing all azimuths 0 -> 360deg, i
> have the coordinates of the "circles" i'm trying to draw (where, by
> "circle", i mean "the set of all points that are r distance from my
> lon/lat").

Is that significantly different than a circle with radius r drawn
in the projected map, if r is about 0.5 degree as yous said
in the original post?

Ciao,
Paolo

>
> thanks all for the help
> chris

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[Message index]

		circles on the sky By: Christopher Thom on Fri, 27 March 2009 10:53
		Re: circles on the sky By: pgrigis on Tue, 31 March 2009 15:45
		Re: circles on the sky By: Christopher Thom on Tue, 31 March 2009 15:27
		Re: circles on the sky By: JDS on Tue, 07 April 2009 07:17
		Re: circles on the sky By: pgrigis on Tue, 31 March 2009 14:20
		Re: circles on the sky By: Christopher Thom on Tue, 31 March 2009 14:07
		Re: circles on the sky By: pgrigis on Tue, 31 March 2009 13:00
		Re: circles on the sky By: Kenneth P. Bowman on Tue, 31 March 2009 12:34

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