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Re: Skymap and Array Problems [message #35752 is a reply to message #35746]

Wed, 09 July 2003 07:28

wissels
Messages: 2
Registered: July 2003

Junior Member

>> Furthermore, the galactic coordinates do not come out in sequential
>> order, so I need to sort them (along with their referenced data
>> points).
>
> This might be. Could you please try to explain the geometry of your grid in
> galactic coordinates. You start out with a rectangular grid in celestial
> coordinates, right? Ie one that can be described by 1D x & y arrays (not
> necessarily evenly spaced). Is the grid in galactic coordinates a distorted
> rectangular grid? Or (as I think you are implying) something more general.

The grid in galactic coordinates is not distorted. The
transformation involves rotation (the galactic plane is 63deg from the
celestial plane) and translation from the earth centered vertex to
vertex at the center of the galaxy.

I must have made the problem sound worse than it is. I'm just
frustrated, because of my lack of understanding in idl.

The main problem is that after conversion the coordinates are not
chronological. Meaning that instead of

Long Lat ..............i get..............Long Lat
-182 -89 12 23
-155 -45 -155 -45
12 23 -189 -89
35 78 35 78

As far as I can tell IDLgrCONTOUR (or CONTOUR for that matter) will
not let me plot well if the coordinates are not sorted. So I have to
sort all three arrays (the latitude set, the longitude set and the
data set) in order to map correctly. I hope that makes my problem a
little clearer. I will try looking at IDLgrPolygon.

Thanks!
Stephanie

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[Message index]

		Re: Skymap and Array Problems By: Mark Hadfield on Wed, 09 July 2003 16:59
		Re: Skymap and Array Problems By: wissels on Wed, 09 July 2003 07:28
		Re: Skymap and Array Problems By: Mark Hadfield on Tue, 08 July 2003 14:43

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