Subject: WhereWhen with Regions

From: Arnold Rots <[email-masked]>
Date: Mon, 5 Dec 2005 17:52:25 -0500 (EST)

Appended is more or less the same example I showed with a region
specification added.  The region is specified in the AstroCoordArea
element, not the Error part of the coordinate element itself.
I used a polygon.
Errors, btw, may be specified as a circle, rectangular box, or ellipse.
I would suggest still putting an error radius in the Error element to
provide a sensible number for clients who are not interested in the
exact details of the region.

  - Arnold

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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                             [email-masked]
USA                                     http://hea-www.harvard.edu/~arots/
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<?xml version="1.0" encoding="UTF-8"?>
<ObsDataLocation xmlns="http://www.ivoa.net/xml/STC/stc-v1.23.xsd"
    xmlns:crd="http://www.ivoa.net/xml/STC/STCcoords/v1.23"
    xmlns:reg="http://www.ivoa.net/xml/STC/STCregion/v1.23"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:xlink="http://www.w3.org/1999/xlink"
    xsi:schemaLocation="http://www.ivoa.net/xml/STC/stc-v1.23.xsd
    http://hea-www.harvard.edu/~arots/nvometa/v1.23/stc-v1.23.xsd">

  <ObservatoryLocation id="KPNO" xlink:type="simple"
       xlink:href="ivo://STClib/Observatories.xml#KPNO"/>

  <ObservationLocation>
    <AstroCoordSystem id="UTC-FK5-TOPO" xlink:type="simple"
       xlink:href="ivo://STClib/AstroCoordSystems.xml#UTC-FK5-TOPO"/>
    <crd:AstroCoords coord_system_id="UTC-FK5-TOPO">
      <crd:Time unit="s">
        <crd:TimeInstant>
          <crd:ISOTime>2005-04-15T23:59:59</crd:ISOTime>
        </crd:TimeInstant>
        <crd:Error>2</crd:Error>
      </crd:Time>
      <crd:Position2D unit="deg">
        <crd:Value2>141.1024 69.3064</crd:Value2>
        <crd:Error2Radius>0.1</crd:Error2Radius>
      </crd:Position2D>
    </crd:AstroCoords>
    <AstroCoordArea coord_system_id="UTC-FK5-TOPO">
      <Region>
        <reg:Polygon unit="deg">
          <reg:Vertex>
            <reg:Position>141.1 69.2</reg:Position>
          </reg:Vertex>
          <reg:Vertex>
            <reg:Position>140.9 69.3</reg:Position>
          </reg:Vertex>
          <reg:Vertex>
            <reg:Position>141.1 69.4</reg:Position>
          </reg:Vertex>
          <reg:Vertex>
            <reg:Position>141.3 69.3</reg:Position>
          </reg:Vertex>
        </reg:Polygon>
      </Region>
    </AstroCoordArea>
  </ObservationLocation>
</ObsDataLocation>