SSAP and images

[Guy Rixon]

Anita,

by my reading of the SSAP spec, the position encoding is part of the  
Spectrum data model:

Coverage.Location.Sky.Value pos.eq RA and Dec deg, R
(or sexagesimal string)

If I understand this correctly, each column of the VOtable returned  
by SSA is a node in the Spectrum data model, with an associated  
Utype. This position node is defined as a coordinate pair, so the  
column isn't a scalar, numeric type. It would have to be either a  
string or an array of float or double. Would the array form work for  
you? I guess the string form covers the case where the coordinates  
are sexagesimal.

Cheers,
Guy

On 1 May 2007, at 17:07, Anita M. S. Richards wrote:

>
> Hi people,
>
> Today we were doing a demo at the E-Science North West open day in  
> Manchester and someone asked 'can you display the positions of  
> spectra on top of images'.  So I used AstroScope to get some  
> spectra and images and sent an image to Aladin, and sent the SSAP  
> VOTable to Aladin and TopCat. Two problems emerged:
>
> The position is given in decimal degrees but type is string.  If I  
> change to float, TopCat will plot the positions.
>
> However, even then, Aladin will only offer to display it in a  
> spectral tool - it won't plot the positions.
>
> Probably we ahve discussed this and there are good reasons for it  
> not working? Or is it something to do with retrieving SSAP stuff  
> via AstroScope? But otherwise, it seems easy to fix and would  
> please users.
>
> Thanks
>
> Anita
>
> - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  
> - - -
> Dr. Anita M. S. Richards, AstroGrid Astronomer
> MERLIN/VLBI National Facility, University of Manchester, Jodrell  
> Bank Observatory, Macclesfield, Cheshire SK11 9DL, U.K. tel +44 (0) 
> 1477 572683 (direct); 571321 (switchboard); 571618 (fax).

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