[ivoa-std/SSA] Invalid UCDs : proposal for an erratum to SSA 1.1: instr.fov

[Mireille LOUYS]

Dear Semantics & DAL members,

I have a proposal here for the revision of the UCD terms in the SSA 
specification.
https://ivoa.net/documents/SSA/20120210/ 
<https://ivoa.net/documents/SSA/20120210/>

Currently
/instr.fov /and /meta.curation / are two terms in the spec which:
- are misused  with respect to the meaning of the element they described 
: /instr.fov/
- or are not//compliant with UCD Rules : meta.curation is defined as 
primary term in UCDList1.4 and used also as secondary term .
/

this mail will discuss the first term :
*instr.fov :*
/The proposed changes for the invalid UCDs in SSAP are the following/, //
/
//

Char.SpatialAxis.Coverage.Bounds.Extent

	

phys.angSize; instr.fov

	

Aperture angular size

	

double

	

Char.SpatialAxis.Coverage.Support.Area

	

pos.outline;instr.fov

	

Aperture region

	

char

	

*

Char.SpatialAxis.Coverage.Support.Extent

	

phys.angArea; instr.fov

	

Field of view area, sq. deg.

	

double

	

//
Rationale :
/instr.fov/ represents a geometrical shape on the sky, where an 
instrument is observing  a signal.

Currently in SSA 1.1, only /instr.fov/ is used  to describe the Aperture 
details.
This does not allow to distinguish between the various properties 
describing this field of view.
'Aperture angular size' is better classified as phys.angSize; instr.fov 
in the UCD vocabulary.

Aperture region, which represents the geometry and points that delimits 
the FoV corresponds to /pos.outline;instr.fov.
pos.outline /was introduced later than the SSA specification, but 
applies fully here. /

/Field of view area, the area in sq. degrees is also a dimension of the 
/instr.fov/ , and not the FoV itself.
/phys.angArea;instr.fov /can do for this case.

UCDList EN-1.4 defines /instr.fov/ as
S | instr.fov | Field of view

This definition is fuzzy, and can be clarified and replaced by
S | instr.fov | Related to Field of view
for the next UCDList update UCDList1.5.

Proposed Action : change definition of instr.fov to Related to field ov 
view .


I expect this to be a first draft to start to write a SSA errata , as 
proposed by Markus earlier.

Any opinion, comments , improvenents you would like to propose?

Many thanks ,
Mireille
/**/

Le 09/09/2021 à 10:16, msdemlei a écrit :
> On Wed, Sep 08, 2021 at 07:18:54AM -0700, Mireille LOUYS wrote:
> > instr.fov represents a geometrical shape on the sky covered by an
> > observing instrument. Table columns should be specified
> > unambiguously to designate what is measured or represented in the
> > column value: phys.angSize;instr.fov , phys.area;instr.fov ,
> > pos.outline;instr.fov
>
> While it may be a nice service to complete UCD assignment in a future
> version of SSAP, I think for the present purpose (remove
> contradictions between different IVOA specs), we should restrict
> ourselves to the UCDs that actually conflict between SSAP and UCD and
> fix those. That's urgent in my book. Anything else may be nice to
> have in order to make SSAP responses more palatable to generic
> clients. But that, I claim, is a rather exotic use case, and anyway
> it doesn't seem particularly urgent.
>
> If you're sure you don't want to adapt UCD to SSAP usage, then it
> seems the only way forward is to write an Erratum for SSAP, and that
> necessarily needs to be restricted to the columns with the invalid
> UCDs.
>
> Who'll write this? Should I?
>
> —
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-- 
--
Mireille Louys,  MCF (Associate Professor)
Centre de données CDS		IPSEO, Images, Laboratoire Icube
Observatoire de Strasbourg	Telecom Physique Strasbourg
11 rue de l'Université		300, Bd Sebastien Brandt CS 10413
F- 67000-STRASBOURG		F-67412 ILLKIRCH Cedex
Tel: +33 3 68 85 24 34

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