VOTable 1.5 Working Draft (2023-09-13)

[Francois Ochsenbein]

Hi Markus, and VOTable friends,

VOTable is an important component in the VO, and I'm really not sure it's
worth to change the VOTable schema as proposed in section 3.4 — and is it
really in the VOTable document that the way of retrieving the astrometric
components should be placed ? Also don't forget that the COOSYS element was
up to now located at the RESOURCE level, and from there you can't safely
reference FIELDs which may exist in several TABLEs; should COOSYS become as
a sub-TABLE element? Could the example proposed at the end of section 3.4
work is there are several TABLEs in the RESOURCE ?

IF there is a need to specify the astrometric components in the VOTable
document (again, I'm not sure the VOTable format definition is the correct
location for this specification) :
* suggest to use a GROUP (example below)
* place an example in the appropriate section (section 4.9).

I really hope that VOTable will continue to fill the necessary requirements
for providing well-documented astronomical data.

Thank you for letting me participate to the discussion !
François Ochsenbein

============================================================

An example could be:

<RESOURCE>
<COOSYS ID="ICRS-geo" system="ICRS" refposition="geocenter" />
<COOSYS ID="ICRS-2016" system="ICRS" epoch="J2016.0"
refposition="barycenter" />
...

<TABLE>

<FIELD ID="col1" name="RA" ucd="pos.eq.ra" unit="deg" ref="ICRS-2016"/>
<FIELD ID="col2" name="Dec" ucd="pos.eq.dec" unit="deg" ref="ICRS-2016"/>
...
<FIELD ID="col11" name="RA-predicted" ucd="pos.eq.ra" unit="deg"
ref="ICRS-geo"//>
<FIELD ID="col12" name="Dec-predicted" ucd="pos.eq.dec" unit="deg"
ref="ICRS-geo"/>
<FIELD ID="col13" name="Date" unit="yr" ucd="time.epoch" >
<FIELD ID="col14" name="AU" unit="au" ucd="pos.distance" >
...

<GROUP name="astrometry-main" ucd="pos" ref="ICRS-2016">
  <DESCRIPTION>Components of the position at the mean epoch</DESCRIPTION>
  <FIELDref ref="col1" utype="LonLatPoint-lon" />
  <FIELDref ref="col2" utype="LonLatPoint-lat" />
  ...
</GROUP>

<GROUP name="astrometry-predicted" ucd="pos" ref="ICRS-geo">
  <DESCRIPTION>Individual geocentric computations at reported
dates</DESCRIPTION>
  <FIELDref ref="col11" utype="LonLatPoint-lon" />
  <FIELDref ref="col12" utype="LonLatPoint-lat" />
  <FIELDref ref="col13" ucd="time.epoch" />
  <FIELDref ref="col14" ucd="pos.distance" />
  ...
</GROUP>
...
</TABLE>
</RESOURCE>

(notice that all elements are defined before these are used; also
non-astrometric parameters may be present in a group, the ucd was then
listed rather than a utype)
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.ivoa.net/pipermail/apps/attachments/20231016/f4e64ee3/attachment.htm>