Spectrum DM and Characterization DM

[Francois Bonnarel]

Dear all,
   I will not speak about the Spectrum/SOAP compatibility
problem, although I think we should concentrate on the model
itself and may allow several implementations, the one proposed
in the document being the first proposed solution, but not the
only solution probably.

   I looked to the spectrum data model and specifically to the utype 
list from the point of the view of the IVOA char datamodel.
I think there is quite good agreement although I think there a couples
of points to be quoted.

    The main structural point is the lack of sampling". For me it is 
only apparent because, actually the SpectrumAxis.accuracy contains the
BinSize.
   But isn't this Spectrum.Char.SpectralAxis.Accuracy.BinSize the
mean sampling Extent/Period ?


     Other point Spectrum.Char.SpectralAxis.Accuracy.StatErr is
distinguished from Spectrum.Char.SpectralAxis.Accuracy.StatErrLow at
the same level, while in char StatErr (and SysErr) are containers 
containig a RefVal, and bounds.


     There a few minor vocabulary points, but it is just a mapping
issue I think:
    eg : Spectrum.Char.SpatialAxis.Location.value is
         Characterization.SpatialAxis.Location.coord in char
because "coord" is actually implemented with stc type AstroCoordType.

    Otherwise, it looks in quite good agreement as far as I saw
*

Other matter the VOTABLE serialisation issues:
     I think organising every relationships with embedded GROUPS is 

 little bit too much. It's fine for aggregations/compositions but not
for simple associations (specially 1 to n) where two different tables
"associated" by a common  index FIELD are a solution with more flexibility.
     

See you soon in Moscow
Regards
François

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Francois   Bonnarel               Observatoire Astronomique de Strasbourg
CDS (Centre de donnees          11, rue de l'Universite
astronomiques de Strasbourg)    F--67000 Strasbourg (France)

Tel: +33-(0)3 90 24 24 11       WWW: http://cdsweb.u-strasbg.fr/people/fb.html
Fax: +33-(0)3 90 24 24 25       E-mail: bonnarel at astro.u-strasbg.fr
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