solar metadata in VODataServiceCoverage schema

[Elizabeth Auden]

Hello,

I recently tried to make a registry entry for the EGSO Solar Event
Catalogue service to see if the IVOA registry schemas needed any
additional metadata elements to cater specifically for solar data
providers.  I found that there were only two elements in the IVOA schemas
suggest themselves for solar metadata extensions: "RegionType" and
"CoordFrameType" in VODataServiceCoverage-v0.2.xsd.

RegionType

Currently, spatial coverage of a data resource can be described as
"AllSky",  or through a range of sky coordinates falling within a box or
circle.   Solar data resources can be described through analogous
coordinate systems, but celestial coordinates are not appropriate.
Several solar observatories and satellites, including Big Bear Solar
Observatory, Kitt Peak, and SOHO, provide full-disk solar data.
Therefore, it is suggested that the element "AllSolarDisk" be added to
VODataServiceCoverage-v0.2.xsd as a sibling element to "AllSky". Example
in a tabularSkyService XML file:

/Coverage/Spatial/Region/AllSolarDisk

CoordFrameType

The CoordFrame element contains an enumeration of celestial coordinate
systems that may be used in describing coordinate ranges or circular
regions.  Adding solar coordinate systems to this list would allow solar
data resources to be described in terms of their spatial coverage on the
Sun.  The Space Environment Information System (SPENVIS) provided by ESA
outlines ten coordinate systems that can be used to describe solar spatial
coverage at http://www.spenvis.oma.be/spenvis/help/system/spenvis.html.
Adding the full list of coordinate systems to the CoordFrame enumeration
would produce these elements (examples in a tabularSkyService XML file):

1. /Coverage/Spatial/CoordFrameType/Spherical
2. /Coverage/Spatial/CoordFrameType/Cartesian
3. /Coverage/Spatial/CoordFrameType/GeocentricEquatorialInertial
4. /Coverage/Spatial/CoordFrameType/Geographic
5. /Coverage/Spatial/CoordFrameType/Geodetic
6. /Coverage/Spatial/CoordFrameType/Geomagnetic
7. /Coverage/Spatial/CoordFrameType/GeocentricSolarEcliptic
8. /Coverage/Spatial/CoordFrameType/GeocentricSolarEquatorial
9. /Coverage/Spatial/CoordFrameType/GeocentricSolarMagnetospheric
10. /Coverage/Spatial/CoordFrameType/SolarMagnetic


cheers,
Elizabeth Auden