Dear Jean-Christophe
Last week we presented at the IVOA Interoperability meeting held in Moscow an updated version of the Source Catalog Data Model. You can have a look at what we have presented so far here
http://www.ivoa.net/internal/IVOA/IvoaDataModel/SourceDM_Moscow_2006.pdf The model is going to be released formally as a new IVOA Working Draft shortly.
Among several changes that we have included, there is one that might be of your interest or may even solve your request. The 'Source' element now points to a 'Coordinates' container , where the equinox, the 2D coordinate values and their respective errors can be specified as attributes. As we try to keep the model as simple as possible and still consistent with the rest of the data models we take the same assumptions as the STC and the Coordinate Data Model do about coordinate frames, equinox and epoch:
"[... ] the token identifying the coordinate system and frame. The usual value is ICRS, which is the standard post-Hipparcos-era RA and Dec with an equinox consistent with J2000. The other systems have different orientation and rotation:
Therefore we have included the equinox attribute only, assuming that the default epochs would label the equinox for FK4 and FK5. We decided to consider the epoch implicitly in the equinox so to start with a simple model. Anyway, if you find it useful, the 'Coordinates' class could be easily extended to include the 'reference frame' and 'epoch' attributes too, where the reference frame would be required (with same set of allowed values as STC and Coordinates Data Model describes) and the epoch optional.
Should you have any other question please let us know.
Cheers,
Inaki Ortiz
Jean-Christophe malapert wrote:
> Dear all,
>
> I would like to use the Source DM in oder to store object coordinates
> and magnitudes. However I don't see the Coordinate system used
> (ICRS,FK5,FK4). Basically, with FK5,Fk4 you need respectively to
> define the equinox and the epoch. Would it be possible to add these
> parameters in the DM ?
>
> Cheers,
> J-Christophe
Received on 2006-09-26Z13:36:20