SSA-1_1-Err-4 < IVOA

IVOA Web>IvoaDAL>SSA-1_1-Errata>SSA-1_1-Err-4 (2024-09-05, GregoryMantelet) (raw view)

---+ SSA v1.1 Erratum 4: Make coverage optional

Author: James Dempsey

Date last changed: 2023-12-04

Date accepted: 2024-08-28

Github Issue: [[https://github.com/ivoa-std/SSA/issues/8][SSA Issue #8]]

---++ <a name="Rationale"></a>Rationale

SSA 1.1 sec 4.2.5.10 states MANdatory coverage information (!Char.SpatialAxis.Coverage.Location.Value + 2 others), but they are missing from the example in Appendix A. Theoretical services cannot provide coverage information so these columns should be made optional to support theoretical services.

---++ <a name="Erratum_Content"></a>Erratum Content

*In section 4.2.5.10*, add the following text at the end of the introductory sentence.

<blockquote> Where coverage information is
available, such as in observational services, the columns !Char.SpatialAxis.Coverage.Location.Value,
!Char.SpatialAxis.Coverage.Bounds.Extent,
!Char.TimeAxis.Coverage.Location.Value,
!Char.SpectralAxis.Coverage.Location.Value, and !Char.SpectralAxis.Coverage.Bounds.Extent should be provided.
 However, this component is optional to support theoretical services and other services which do not have coverage information. </blockquote>

and in the table in that section change the value in the Req column from MAN to REC for the following rows:

| UTYPE | Description | Req | Default |
| !Char.SpatialAxis.Coverage.Location.Value | Observed position, e.g., RA DEC | *REC* | |
| !Char.SpatialAxis.Coverage.Bounds.Extent | Aperture angular diameter, deg | *REC* | |
| !Char.TimeAxis.Coverage.Location.Value | Midpoint of exposure (MJD) | *REC* | |
| !Char.SpectralAxis.Coverage.Location.Value | Midpoint of Spectral coord range | *REC* | |
| !Char.SpectralAxis.Coverage.Bounds.Extent | Width of spectrum in meters | *REC* | |

---++ <a name="Impact_Assessment"></a>Impact Assessment

By loosening the requirements for positional description of the spectra,
existing theory services will be able to be compliant. Clients will need
to allow for the coverage fields to be missing.  However, they already
need to do that for established SSA theory services, of which there are
at least five at this point; !RegTAP query:

<pre>select count(ivoid)
from rr.res_detail
where detail_xpath='/capability/dataSource'
and detail_value like 'theor%'
</pre>

<br />
<!-- * Set ALLOWTOPICRENAME = IVOA.TWikiAdminGroup -->

Topic revision: r4 - 2024-09-05 - GregoryMantelet

IVOA

Log in or Register

IVOA.net
Wiki Home
WebChanges
WebTopicList
WebStatistics

Twiki Meta & Help
IVOA
Know
Main
Sandbox
TWiki

TWiki intro
TWiki tutorial
User registration
Notify me

Working Groups

Interest Groups

Committees

Stds&Procs

www.ivoa.net
Documents
Events
Members
XML Schema