VOTable discussions

1
VOTable discussions

• Concerns about how
• units
• date/time (ISO8601) -- no new datatype!
• sexagesimal
• are expressed in VOTable and other VO components
• ? need common solutions in VO components!
• Concerns about VOTable recursivity (kept)
• Concerns about conservation of VOTable structures
  in applications (TOPcat)
• ? will be fixed

2
The utype question

• incorporated in VOTable 1.1
• (VOTable is a serialization of parameters which
  may originate from any part of the VO)
• Role give a fully detailed meaning by a
  reference to an external data model, e.g.
• systems in which values are expressed
  (photometry)
• reference frames used for space / time / etc
  (STC)
• (ucd broad semantics)
• Used in other VO components (DAL), look for
  generic and common solutions.

3
utype example for Regions(static model)
ltstcCirclegt ltstcCenter unit"deg"gt
ltstcC1gt233.737917lt/stcC1gt
ltstcC2gt23.503330lt/stcC2gt lt/stcCentergt
ltstcRadius pos_unit"arcsec"gt12.0lt/stcRadiusgt lt/
stcCirclegt
ltFIELD ID"Col1" name"cRA"
utype"stcCircle.Center.C1" ucd"pos.eq.ra"
unit"deg" datatype"double" /gt ltFIELD ID"Col2"
name"cDec" utype"stcCircle.Center.C2"
ucd"pos.eq.dec" unit"deg" datatype"double"
/gt ltPARAM name"targetRadius"
utype"stcCircle.Radius" ucd"pos.angDistance"
datatype"double" unit"arcsec" value"12.0"/gt
4
utype example for Regions(dynamic model)
ltstcPolygongt ltstcVertexgt ltstcPositiongt
ltstcC1gt233.737917lt/stcC1gt
ltstcC2gt23.503330lt/stcC2gt lt/stcPositiongt
lt/stcVertexgt ltstcVertexgt ltstcPositiongt
... ... ... ... lt/stcPolygongt
ltGROUP name"myPolygon" utype"stcPolygon"gt
ltFIELDref ref"vert1"gt ltFIELDref ref"vert2"gt
ltFIELDref ref"vert3"gt lt/GROUPgt ltFIELD
ID"Vert1" name"point1" utype"stcPolygon.Ver
tex" ucd"pos.eq" unit"deg" arraysize"2"
datatype"double" /gt ltFIELD ID"Vert2"
name"point2" utype"stcPolygon.Vertex"
ucd"pos.eq" unit"deg" arraysize"2"
datatype"double" /gt ...
5
STC reference via utype
ltGROUP ucd"pos"gt ltPARAM utype"stcAstroCoordSy
stem.SpaceFrame.Name"
datatype"char" arraysize""
name"coosys" value"ICRS" /gt ltFIELDref
ref"col1"/gt ltFIELDref ref"col2"/gt ltPARAM
name"Epoch" utype"stcAstroCoordSystem.
SpaceFrame.Epoch" datatype"double"
value"1991.25" /gt lt/GROUPgt ltFIELD
ID"col1" name"RA" datatype"double"
utype"stcAstroCoords.Position2D.C1"
unit"deg" /gt ltFIELD ID"col2" name"Dec"
datatype"double" utype"stcAstroCoord
s.Position2D.C2" unit"deg" /gt
6
VOTable Roadmap

• Referencing STC via utype
• proposal (Jonathan) ? June 2006
• discussion of proposals (July -- August)
• take a decision at next IVOA in September 2007
• Toward a new schema (to be discussed in
  September)
• details about utype conventions and recommended
  usage
• deprecate COOSYS
• rationalized (closer to Java usage)