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Hi Mark , Hi everyone, <br>
<br>
I discussed with Sebastien and Andrea about this usage of
"instr.fov" .<br>
<br>
I added some preliminary checks we did in <i>slanted font </i>for
each line in the table provided to understand the origin of the
error usage.<br>
( see below).<br>
<br>
We did find "instr.fov;instr.pixel" in Vizier due to an error in a
mapping table between UCD1 and UCD1+. <br>
This will be corrected. <br>
<br>
In the SSAP rec, 'instr.fov' is misused 2 times in page 66.<br>
"instr.fov", represents an instrument characteristics projected on
the sky. <br>
It does not exist <i>per se</i> as a physical quantity, with units
etc.<br>
<br>
It is suitable to be a qualifier, to some measurement like <br>
E phys.angSize --> phys.angSize;instr.fov <br>
Q phys.angArea --> phys.angArea;instr.fov <br>
<br>
Other errors appear for several other fields . <br>
we 'll check the other UCD in SSAP and propose some updates to the
spec as an errata very soon. <br>
<br>
<br>
<div class="moz-cite-prefix">Le 20/07/2021 à 10:49, Mark Taylor a
écrit :<br>
</div>
<blockquote type="cite"
cite="mid:alpine.DEB.2.21.2107200943080.4150@IT076926">
<pre class="moz-quote-pre" wrap="">On Thu, 8 Jul 2021, Markus Demleitner wrote:
</pre>
<blockquote type="cite">
<pre class="moz-quote-pre" wrap="">Dear Colleagues,
SSAP 1.1 requires the UCD instr.fov on a few columns (cf. p.66 of
<a class="moz-txt-link-freetext" href="https://ivoa.net/documents/SSA/20120210/REC-SSA-1.1-20120210.pdf">https://ivoa.net/documents/SSA/20120210/REC-SSA-1.1-20120210.pdf</a>).
Trouble is: By UCDList 1.4, instr.fov is a secondary UCD, so the
UCD required by SSA is illegal by UCD.
How do we fix this? I see two ways forward: Either we lift the S
restriction on instr.fov. This would sound reasonable to me and
obviously many others; here's a few counts from today's
rr.table_columns:
instr.fov | 198 <i>spectra services</i> appling SSAP
instr.fov;instr.pixel | 2475 <i>most are Vizier tables : error in a translation script UCD1--> UCD1+</i>
phys.angsize;instr.fov | 167 <i>appropriate usage</i> and suggested by cds assigning tool <a moz-do-not-send="true" href="http://cdsweb.u-strasbg.fr/UCD/cgi-bin/descr2ucd">http://cdsweb.u-strasbg.fr/UCD/cgi-bin/descr2ucd</a>
pos.angdistance;instr.fov | 16 <i>correct ucd syntax but semantically ambiguous with instr.fov : distance is not size </i>
pos.posang;instr.fov | 12 <i>correct ucd syntax but check context </i>
(these are the most popular ones).
Or we write an erratum to SSAP changing the required UCD to, I think,
phys.angsize;instr.fov .
Me, I don't have much of an opinion, though I have to admit I can't
really say why there's the S on instr.fov.
There is a similar problem in SLAP, where a UCD em.line is required,
which also is S in the UCD list. I'd be a lot more relaxed about
that since I believe SLAP as a whole ought to make room for something
closer to VAMDC.
</pre>
</blockquote>
</blockquote>
<blockquote type="cite"
cite="mid:alpine.DEB.2.21.2107200943080.4150@IT076926">
<pre class="moz-quote-pre" wrap="">
My take: presumably somebody thought that it made sense to have
instr.fov and em.line as primary UCDs, so my first instinct would
be to change their designation from S (secondary) to Q (both) in
UCD1+, at least for 1.5, and maybe as an erratum to 1.4.
This approach would be less disruptive than a change to SSA/SLAP,
since only the validators have to change, not the services
or clients.
To assess whether that's sensible, can one of the UCD1+ authors
or other Semantics representative either agree that's reasonable
or present an argument that these ought not to be Primary?
(Context: future versions of taplint will check UCDs for validity
against the UCD1+ list, so there may be quite a few services that
see taplint errors reported against tables that are following
standard requirements).
Mark
--
Mark Taylor Astronomical Programmer Physics, Bristol University, UK
<a class="moz-txt-link-abbreviated" href="mailto:m.b.taylor@bristol.ac.uk">m.b.taylor@bristol.ac.uk</a> <a class="moz-txt-link-freetext" href="http://www.star.bristol.ac.uk/~mbt/">http://www.star.bristol.ac.uk/~mbt/</a>
</pre>
</blockquote>
<br>
<pre class="moz-signature" cols="72">--
--
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</pre>
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