VOTable session @ Interop.Moscow

[Arnold Rots]

Francois,

I looked at the three scenarios and suggest some minor changes to
encapsulate the linkages between various STC components, without using
FIELDrefs.

Two versions (one using the "enumerated" element names and one using
Jonathan's Types) are appended.  I am still a bit hesitant about thos
types since it is not a real enumeration, but I don't think it is a
big deal.

Note that I have linked the STC coordinates and coordinate system
through the STC-provided id tags, but that I then link the FIELDs
through VOTable ID tags to the parent element they belong to.
Coords1 is a completely arbitrary string, of course - as is
TT_ICRS_TOPO, but one may prefer more or less meaningful tags.

I think this would be a robust and elegant solution.

  - Arnold

Francois Ochsenbein wrote:
> 
> Hi VOTablers,
> 
> The attendence at this IVOA session is rather sparse -- and we were
> just 8 persons at the VOTable session. Quite easy to take decisions,
> but a larger consensus is wished...
> 
> The viewgraphs are available from 
> http://www.ivoa.net/twiki/bin/view/IVOA/InterOpSep2006VOTable
> The wiki page contains in particular links to 3 scenarios 
> to express the link to STC for the definition of the coordinate
> system which should replace the COOSYS currently used mechanism.
> The preference of the group was clearly for scenario #2. If there is
> opposition, it's better to shout now.
> 
> Other topics discussed which might be of interest: slight changes in
> the schema (addition of an ID attribute in the TR to make most
> code generator happier about TABLEDATA class, question of empty TD's (null
> values in columns), sexagesimal usage, referencing TABLE objects.
> 
> --Francois
> ================================================================================
> Francois Ochsenbein       ------       Observatoire Astronomique de Strasbourg
>    11, rue de l'Universite F-67000 STRASBOURG       Phone: +33-(0)390 24 24 29
> Email: francois at astro.u-strasbg.fr   (France)         Fax: +33-(0)390 24 24 17
> ================================================================================
> 
--------------------------------------------------------------------------
Arnold H. Rots                                Chandra X-ray Science Center
Smithsonian Astrophysical Observatory                tel:  +1 617 496 7701
60 Garden Street, MS 67                              fax:  +1 617 495 7356
Cambridge, MA 02138                             arots at head.cfa.harvard.edu
USA                                     http://hea-www.harvard.edu/~arots/
--------------------------------------------------------------------------


STC representation:

<?xml version="1.0" encoding="UTF-8"?>
<TABLE ID="M81">
<GROUP utype="stc:AstroCoordSystem" >
   <PARAM utype="stc:AstroCoordSystem.id" value="TT_ICRS_TOPO"/>
   <GROUP utype="stc:AstroCoordSystem.TimeFrame" >
     <PARAM utype="stc:AstroCoordSystem.TimeFrame.TimeScale" value="TT" />
     <PARAM utype="stc:AstroCoordSystem.TimeFrame.TOPOCENTER" value="" />
   </GROUP> 
   <GROUP utype="stc:AstroCoordSystem.SpaceFrame" >
     <PARAM utype="stc:AstroCoordSystem.SpaceFrame.ICRS" value="" />
     <PARAM utype="stc:AstroCoordSystem.SpaceFrame.TOPOCENTER" value="" />
     <PARAM utype="stc:AstroCoordSystem.SpaceFrame.SPHERICAL" value="" />
   </GROUP>
</GROUP>
<GROUP ID="Coords1" utype="stc:AstroCoords">
   <PARAM utype="stc:AstroCoords.coord_sys_id" value="TT_ICRS_TOPO"/>
</GROUP>

<FIELD ID="OT" name="ObservingTime" datatype="char" arraysize="19"
       utype="stc:AstroCoords.Time.TimeInstant.ISOTime"  ref="Coords1" />
<FIELD ID="RA" name="Right Ascension" datatype="double" unit="deg"
       utype="stc:AstroCoords.Position2D.Value2.C1"  ref="Coords1" />
<FIELD ID="DEC" name="DEClination" datatype="double" unit="deg"
       utype="stc:AstroCoords.Position2D.Value2.C2" ref="Coords1" />
<FIELD ID= "Err1" name="RA_Error" datatype="float" unit="arcsec"
       utype="stc:AstroCoords.Position2D.Error2.C1" ref="Coords1" />
<FIELD ID= "Err2" name="DEC_Error" datatype="float" unit="arcsec"
       utype="stc:AstroCoords.Position2D.Error2.C2" ref="Coords1" />
</TABLE>



And the same using Types:

<?xml version="1.0" encoding="UTF-8"?>
<TABLE ID="M81">
<GROUP utype="stc:AstroCoordSystem" >
   <PARAM utype="stc:AstroCoordSystem.id" value="TT_ICRS_TOPO"/>
   <GROUP utype="stc:AstroCoordSystem.TimeFrame" >
     <PARAM utype="stc:AstroCoordSystem.TimeFrame.TimeScale" value="TT" />
     <PARAM utype="stc:AstroCoordSystem.TimeFrame.ReferencePosition.Type" value="TOPOCENTER" />
   </GROUP> 
   <GROUP utype="stc:AstroCoordSystem.SpaceFrame" >
     <PARAM utype="stc:AstroCoordSystem.SpaceFrame.CoordRefFrame.Type" value="ICRS" />
     <PARAM utype="stc:AstroCoordSystem.SpaceFrame.ReferencePosition.Type" value="TOPOCENTER" />
     <PARAM utype="stc:AstroCoordSystem.SpaceFrame.CoordFlavor.Type" value="SPHERICAL" />
   </GROUP>
</GROUP>
<GROUP ID="Coords1" utype="stc:AstroCoords">
   <PARAM utype="stc:AstroCoords.coord_sys_id" value="TT_ICRS_TOPO"/>
</GROUP>

<FIELD ID="OT" name="ObservingTime" datatype="char" arraysize="19"
       utype="stc:AstroCoords.Time.TimeInstant.ISOTime"  ref="Coords1" />
<FIELD ID="RA" name="Right Ascension" datatype="double" unit="deg"
       utype="stc:AstroCoords.Position2D.Value2.C1"  ref="Coords1" />
<FIELD ID="DEC" name="DEClination" datatype="double" unit="deg"
       utype="stc:AstroCoords.Position2D.Value2.C2" ref="Coords1" />
<FIELD ID= "Err1" name="RA_Error" datatype="float" unit="arcsec"
       utype="stc:AstroCoords.Position2D.Error2.C1" ref="Coords1" />
<FIELD ID= "Err2" name="DEC_Error" datatype="float" unit="arcsec"
       utype="stc:AstroCoords.Position2D.Error2.C2" ref="Coords1" />
</TABLE>