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Re: FITS WCS routines [message #72247 is a reply to message #72246] Thu, 19 August 2010 13:49 Go to previous message
wlandsman is currently offline  wlandsman
Messages: 743
Registered: June 2000
Senior Member
On Aug 19, 3:51 pm, Jeremy Bailin <astroco...@gmail.com> wrote:
> Does anyone know of a good IDL implementation or wrapper of up-to-date
> routines to deal with world coordinate systems in FITS files? The ones
> in the astronomy library aren't sufficient - in particular, I need
> something that can deal with a TNX coordinate system (tangent point
> plane with distortions).

Well, to be fair, there is no established standard yet for
representing distortions within FITS. (There is a draft standard
that has been in the works for at least 10 years -- but nobody uses
it ( see Paper IV in
http://www.atnf.csiro.au/people/mcalabre/WCS/index.html )

The TNX distortion keywords and convention were created by the IRAF
software group ( http://fits.gsfc.nasa.gov/registry/tnx.html ). I
have implemented a more popular distortion convention -- the Simple
Imaging Polynomial or SIP (
http://fits.gsfc.nasa.gov/registry/sip.html ) in the Astronomy
Library. Unfortunately, that won't help you if you are given files
using the TNX keywords.

I think I once saw IDL code for parsing the TNX keywords but I can't
remember where just now. Perhaps someone else will have idea. --
Wayne
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