spectral data

[Steve Lowe]

Anita Richards wrote:

>In response to Frank Valdes' comprehensive and very readable posting,
>  
>
>>However, the 4D proposal is to not make the extension too general, and
>>hence, complex. Instead, simply add two parameters to cover the vast
>>majority of observational parameter space of interest to astronomers.
>>    
>>
>
>Unfortunately - or fortunately - that is a very dangerous thing to say.
>Polarization is one example of extra axes in image data, let alone other
>sorts of data like time-series along moving coordinates or visibility
>data.
>
>Just one example in the image domain: Monitioring of SiO maser emission.
>Experiments currently published produce:
>Multiple epochs of RA-Dec-Frequency datacubes  (4 axes)
>in Stokes I Q U V			       (another 4 axes?)
>in 2 or more lines of SiO	               (another >2 axes?)
>  
>
I'd be interested on your comments on the SAO/CfA proposal on SIAP, 
which is in the us-vo data repository. The direct link is:
http://bill.cacr.caltech.edu/cfdocs/usvo-pubs/files/ACFE3.pdf

A key element in the proposal is that services have a way of enumerating 
the data axes that can be used in a query, both for defining the search 
region and for requesting a specific type of data product. That way a 
service can be as limited or as general as needed for the data 
collection it is serving.

The document is only the first part of the plan we are working on, so I 
apologize if it is not transparent on some points. We're trying to flesh 
out the implications and develop a more complete proposal. Also, we're 
not totally committed to some of the syntactic choices presented, and, 
indeed, you'll see that in some places alternatives are presented.

Any comments you have will be appreciated.

Regards,
Steve


-- 
Steve Lowe
Smithsonian Astrophysical Observatory
Harvard-Smithsonian Center for Astrophysics
slowe at cfa.harvard.edu
1-617-496-1661