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Dear all,</div>
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Apologies for butting in as a lurking user, but if the many service providers can be persuaded to be more consistent in the sexagesimal format required for queries this would save users many hours!
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CDS at least provides examples and documentation. But there are so many variants out there (including ALMA using 12.12.12.12 for +12:12:12.12 Dec) that it is usually impossible to take a list from one data provider and use it to query another without extensive
use of SED or whatever... If standardisation is not possible is there any chance of developing and providing translation code to service providers so that if I entered e.g. 12h12m12.12s +12d12m12.1s or any likely variant, this would be translated into whatever
their service needed? <br>
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<div style="font-family:Tahoma; font-size:13px">many thanks</div>
<div style="font-family:Tahoma; font-size:13px">Anita<br>
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<span style="font-family:Arial,Helvetica,sans-serif; font-size:12pt">--------------------------------------------------------------------------------------------------------</span><br>
<span style="font-family:Arial,Helvetica,sans-serif; font-size:12pt">Dr. A.M.S. Richards</span></div>
<div style="font-family:Tahoma; font-size:13px"><span style="font-family:Arial,Helvetica,sans-serif; font-size:12pt">Senior visiting fellow, JBCA, University of Manchester, M13 9PL
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<span style="font-family:Arial,Helvetica,sans-serif; font-size:12pt">a.m.s.richards@manchester.ac.uk (please do not use old @jb.man.ac.uk email)</span></div>
<div style="font-family:Tahoma; font-size:13px"><span style="font-size:12pt; font-family:Arial,Helvetica,sans-serif">I work the hours which suit me. I do not expect instant replies, I respect whatever</span><span style="font-size:12pt; font-family:Arial,Helvetica,sans-serif">
hours you work.</span><br>
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<div id="divRplyFwdMsg" dir="ltr"><font style="font-size:11pt" face="Calibri, sans-serif" color="#000000"><b>From:</b> dal-bounces@ivoa.net <dal-bounces@ivoa.net> on behalf of Mark Taylor <m.b.taylor@bristol.ac.uk><br>
<b>Sent:</b> 10 March 2022 17:17<br>
<b>To:</b> semantics@ivoa.net <semantics@ivoa.net><br>
<b>Cc:</b> Gilles Landais <gilles.landais@astro.unistra.fr>; dal@ivoa.net <dal@ivoa.net><br>
<b>Subject:</b> Sexagesimal metadata</font>
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<div class="PlainText">Dear Semantics and DAL,<br>
<br>
following the report I gave on VOUnit usage in the VO at the last interop<br>
(<a href="https://wiki.ivoa.net/internal/IVOA/InterOpNov2021Ops/uuc.pdf">https://wiki.ivoa.net/internal/IVOA/InterOpNov2021Ops/uuc.pdf</a>)<br>
Gilles Landais at CDS has done a good job of tidying up the units<br>
reported by VizieR to conform to the VOUnit standard (the results are<br>
not yet visible in the public VizieR service).<br>
<br>
But one issue that remains is how to flag up sexagesimal quantities,<br>
which are currently marked up like this:<br>
<br>
<FIELD name="RAJ2000" ucd="pos.eq.ra;meta.main" ref="J2000" <br>
datatype="char" arraysize="12" unit="'h:m:s'"><br>
<FIELD name="DEJ2000" ucd="pos.eq.dec;meta.main" ref="J2000" <br>
datatype="char" arraysize="13" unit="'d:m:s'"><br>
<br>
The unit, by long VizieR tradition, is quoted as 'h:m:s' or 'd:m:s'<br>
(including the single quotes), which is probably recognised as an<br>
ad hoc indication by quite a bit of client code out there. <br>
However this is not legal VOUnit syntax, and they're not really units <br>
anyway since the columns they apply to are not numeric, but it's not <br>
obvious how to indicate sexagesimal content of columns in VOTable metadata.<br>
You can infer it by noticing ucd="pos.eq.*" and datatype="char",<br>
but it seems like there ought to be a more explicit way to do this, <br>
especially considering how common this case is in the tables we deal <br>
with.<br>
<br>
So: what would be the VO-compliant way for CDS to proceed here?<br>
(note I'm not claiming that they are going to follow any such advice,<br>
that's for Gilles to decide). Do we just leave consumers to make a<br>
good guess based on UCD and datatype? Could it be a job for DALI/xtype?<br>
Something else?<br>
<br>
Mark<br>
<br>
--<br>
Mark Taylor Astronomical Programmer Physics, Bristol University, UK<br>
m.b.taylor@bristol.ac.uk <a href="http://www.star.bristol.ac.uk/~mbt/">http://www.star.bristol.ac.uk/~mbt/</a><br>
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