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Old May 6th 09, 07:54 AM posted to sci.astro.fits
David Berry
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Posts: 4
Default [fitsbits] frequency definitions

It looks like Tom's query was about dual sideband data, which is not
covered by paper III. OBSFREQ, etc, are not in the standard. There are
probably various different schemes in use out there. For instance JCMT
and CLASS software use a system based on a keyword called IMAGFREQ,
which holds the image sideband rest frequency (with RESTFREQ holding
the observed sideband rest frequency).


2009/5/5 LC's No-Spam Newsreading account :
On Mon, 4 May 2009, Tom Kuiper wrote:

I'd like to get it clear in my mind what the various frequency
definitions are. *Is the following right? If there is a place where
all this is clearly laid ou, please refer me to that.

Not a spectral WCS expert, but the standard and official references
are :

* the latest release of the FITS standard, in particular chapter 8

- the full WCS paper III, either as published or

* (the other WCS papers are all listed in

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