[fitsbits] frequency definitions

[Tom Kuiper]

Well, not specifically about dual sideband data but about radio spectral 
line data in general.  The best description of the relevant keywords 
that I've found is in the NRAO AIPS++ documentation at 
http://aips2.nrao.edu/docs/notes/236/node14.html.  However, the 
definitions are not entirely unambiguous.  That's why I posted my 
interpretation, to see if anyone disagreed.

Regards

Tom

David Berry wrote:
> 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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