[fitsbits] frequency definitions

[David Berry]

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).

David


2009/5/5 LC's No-Spam Newsreading account <nospam at mi.iasf.cnr.it>:
> 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 :
>
> - http://fits.gsfc.nasa.gov/fits_standard.html
>   the latest release of the FITS standard, in particular chapter 8
>
> - the full WCS paper III, either as published or
>   http://www.atnf.csiro.au/people/mcalabre/WCS/scs.pdf
>
>   (the other WCS papers are all listed in
>   http://www.atnf.csiro.au/people/mcalabre/WCS/index.html
>
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