Expressing position in RDF

[Ed Shaya]

Matthew Graham wrote:
> Hi,
>
> A practical semantic astronomy question:
>
> I want to represent the relationship "object has a RA of 134.556" as 
> an RDF triple. Is there any existing ontology that would allow me to 
> do this? The best I've seen so far is to use the UCD as the predicate.
>
>     Cheers,
>
>     Matthew 
It is usually not a good idea to put out a question late on Friday 
afternnoon before a 3 day holiday, if you want a fast response.

Here is "MyStar has a J2000 RA of 34.5343 degrees, it would be something 
like this in N3:

:MyStar a a:star;
       ivoa:hasPosition :MyCoordinates.

:MyCoordinates a a:J2000Coordinates;                                      
                  geo:hasCoordinate :myRA.

:MyRA a a:rightAscension;
      q:hasFloat 34.5343^^xsd:float;
      q:hasUnits ui:degree.

The following is extracted from an RDF/XML  generated by Protege4_beta.

     <owl:Class rdf:about="#J2000Coordinates">
        <rdfs:subClassOf rdf:resource="&a;equatorialCoordinates"/>
    </owl:Class>

      <!-- http://archive.astro.umd.edu/ont/IVOAO.owl#MyStar -->

    <a:star rdf:about="#MyStar">
        <ivoao:hasPosition rdf:resource="#MyCoordinates"/>
    </a:star>
    <!-- http://archive.astro.umd.edu/ont/IVOAO.owl#MyCoordinates -->

    <J2000Coordinates rdf:about="#MyCoordinates">
        <geo:hasCoordinate rdf:resource="#MyRA"/>
    </J2000Coordinates>
  
    <!-- http://archive.astro.umd.edu/ont/IVOAO.owl#MyRA -->

    <a:rightAscension rdf:about="#MyRA">
        <q:hasFloat rdf:datatype="&xsd;float">34.5343</q:hasFloat>
        <q:hasUnits rdf:resource="&ui;degree"/>
    </a:rightAscension>

Normally, I would put a hasValue FloatValue between MyRa and hasFloat,
but it is probably workable this way also.

Why do you ask?