SSAP and images

[Doug Tody]

Odd, this old email from May 1 just appeared here today.  We already 
discussed this, but I just wanted to add a note that sexagesimal
coordinates are NOT permitted in this context.   - Doug


On Tue, 1 May 2007, Guy Rixon wrote:

> 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).
>