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<p>Dear all,</p>
<p>A couple of monthes ago, after the last release of the Obscore
extension draft by the Tucson interop a couple of emails adressed
the instrumental details issue</p>
<p>here is a compilation (also available now on github and on the
ivoa twiki)</p>
<p>
<blockquote type="cite">
<h3 dir="ltr"
style="padding: 0.25em 10px; margin: 1.25em -10px 0.35em; font-weight: bold; line-height: 1em; font-size: 18.1545px; display: block; border-width: 0px 0px 1px; border-style: solid; height: auto; background-color: rgb(255, 255, 255); color: rgb(99, 0, 0); border-color: rgb(226, 226, 226); font-family: arial, verdana, sans-serif; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; letter-spacing: normal; orphans: 2; text-align: left; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">instrumentation
details</h3>
<p dir="ltr"
style="margin: 1em 0px 0px; background-color: rgb(255, 255, 255); color: rgb(0, 0, 0); font-family: arial, verdana, sans-serif; font-size: 13.65px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: left; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;"></p>
<p
style="margin: 1em 0px 0px; background-color: rgb(255, 255, 255); color: rgb(0, 0, 0); font-family: arial, verdana, sans-serif; font-size: 13.65px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: left; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">Another
somewhat questionable example is use case 1.10. The minimum
number of antennas for a "good" observation really is
instrument-specific and the maximum distance between antennas
really is just a very poor way of expressing a resolution or
uv-coverage constraint for which we already have columns. So
unless someone can come up with a scientific use case for
these parameters, I think they should be dropped from the
extension.</p>
<p
style="margin: 1em 0px 0px; background-color: rgb(255, 255, 255); color: rgb(0, 0, 0); font-family: arial, verdana, sans-serif; font-size: 13.65px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: left; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">--<span> </span><a
class="twikiLink"
href="https://wiki.ivoa.net/twiki/bin/view/IVOA/MarkKettenis"
style="text-decoration: none; color: rgb(69, 113, 208); background-color: transparent; border-color: rgb(69, 113, 208); border-style: none none dotted; border-width: 1px;">MarkKettenis</a><span> </span>2023-11-10</p>
<p
style="margin: 1em 0px 0px; background-color: rgb(255, 255, 255); color: rgb(0, 0, 0); font-family: arial, verdana, sans-serif; font-size: 13.65px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: left; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">Apologies
that I have not been following this in detail but whilst I
agree with Mark that 1.10 is not a realistic use case,
selection by uv coverage is, but just the number of antennas
and extrema of baseline lengths is not enough. On the other
hand, often all archives provide is baseline length (or even
just antenna positions), frequency, pointing direction and
observation duration. Metrics related to uv coverage density
can then easily be calculated (as in the L5 and L80 etc.
metrics in the ALMA archive) but I don't know if this is
commonly seachable directly for any archive. So it is not just
a matter of what is commonly searched for, but also what
archives provide and how much there can be an interface to
convert the latter to the former. --<span> </span><a
class="twikiLink"
href="https://wiki.ivoa.net/twiki/bin/view/IVOA/AnitaRichards"
style="text-decoration: none; color: rgb(69, 113, 208); background-color: transparent; border-color: rgb(69, 113, 208); border-style: none none dotted; border-width: 1px;">AnitaRichards</a><span> </span>2023-11-10</p>
<p
style="margin: 1em 0px 0px; background-color: rgb(255, 255, 255); color: rgb(0, 0, 0); font-family: arial, verdana, sans-serif; font-size: 13.65px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: left; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">The
columns the<span> </span><a class="twikiLink"
href="https://wiki.ivoa.net/twiki/bin/view/IVOA/DaCHS"
style="text-decoration: none; color: rgb(69, 113, 208); background-color: transparent; border-color: rgb(69, 113, 208); border-style: none none dotted; border-width: 1px;">DaCHS</a><span> </span>extension
now offers are f_resolution, instrument_ant_diameter,
instrument_ant_max_dist, instrument_ant_min_dist,
instrument_ant_number, instrument_feed, obs_publisher_did,
s_fov_max, s_fov_min, s_maximum_angular_scale,
s_resolution_max, s_resolution_min, scan_mode, t_exp_max,
t_exp_mean, t_exp_min, tracking_mode, uv_distance_max,
uv_distance_min, uv_distribution_ecc, uv_distribution_fill</p>
<p
style="margin: 1em 0px 0px; background-color: rgb(255, 255, 255); color: rgb(0, 0, 0); font-family: arial, verdana, sans-serif; font-size: 13.65px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: left; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">(select
column_name from tap_schema.columns where
table_name='ivoa.obs_radio' order by column_name)</p>
<p
style="margin: 1em 0px 0px; background-color: rgb(255, 255, 255); color: rgb(0, 0, 0); font-family: arial, verdana, sans-serif; font-size: 13.65px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: left; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">This
doesn't mean I'm convinced all of them should be in. But it
does mean that I'm pretty sure all others should go from table
1; in particular, the "via<span> </span><a class="twikiLink"
href="https://wiki.ivoa.net/twiki/bin/view/IVOA/DataLink"
style="text-decoration: none; color: rgb(69, 113, 208); background-color: transparent; border-color: rgb(69, 113, 208); border-style: none none dotted; border-width: 1px;">DataLink</a>"
things I think are just confusing in there.</p>
<p
style="margin: 1em 0px 0px; background-color: rgb(255, 255, 255); color: rgb(0, 0, 0); font-family: arial, verdana, sans-serif; font-size: 13.65px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: left; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">--<span> </span><a
class="twikiLink"
href="https://wiki.ivoa.net/twiki/bin/view/IVOA/MarkusDemleitner"
style="text-decoration: none; color: rgb(69, 113, 208); background-color: transparent; border-color: rgb(69, 113, 208); border-style: none none dotted; border-width: 1px;">MarkusDemleitner</a><span> </span>2023-12-11</p>
<p
style="margin: 1em 0px 0px; background-color: rgb(255, 255, 255); color: rgb(0, 0, 0); font-family: arial, verdana, sans-serif; font-size: 13.65px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: left; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">I
raised my concerns about the instrument_* columns during the<span> </span><span
class="twikiNewLink"><a
href="https://wiki.ivoa.net/twiki/bin/edit/IVOA/InterOp?topicparent=IVOA.ObsCoreExtensionForRadioData;nowysiwyg=0"
rel="nofollow"
title="InterOp (this topic does not yet exist; you can create it)"
style="text-decoration: none; color: rgb(183, 53, 30); background-color: transparent; border-color: rgb(183, 53, 30); border-style: none none dotted; border-width: 1px;">InterOp</a></span>.
Those really are instrument specific and therefore not very
useful in generic queries one would issue to multiple TAP
services. It may make more sense to provide this information
in an observatory specific table (see for example the
presentation by Greg Sleap on how the MWA presents information
like this).</p>
<p
style="margin: 1em 0px 0px; background-color: rgb(255, 255, 255); color: rgb(0, 0, 0); font-family: arial, verdana, sans-serif; font-size: 13.65px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: left; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">--<span> </span><a
class="twikiLink"
href="https://wiki.ivoa.net/twiki/bin/view/IVOA/MarkKettenis"
style="text-decoration: none; color: rgb(69, 113, 208); background-color: transparent; border-color: rgb(69, 113, 208); border-style: none none dotted; border-width: 1px;">MarkKettenis</a><span> </span>2023-12-13</p>
<p
style="margin: 1em 0px 0px; background-color: rgb(255, 255, 255); color: rgb(0, 0, 0); font-family: arial, verdana, sans-serif; font-size: 13.65px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: left; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">-
Given that<span> </span><a class="twikiLink"
href="https://wiki.ivoa.net/twiki/bin/view/IVOA/ObsCore"
style="text-decoration: none; color: rgb(69, 113, 208); background-color: transparent; border-color: rgb(69, 113, 208); border-style: none none dotted; border-width: 1px;">ObsCore</a><span> </span>is
meant for data discovery, any instrument specific details
should be removed as much as possible, to make sure that a
cross-ObsTAP-service-query will Just Work ™. That there may be
a (defined) mechanism to get to instrument specifics would be
important to have - e.g. for visibility data te u,v-plane
characterisation. These could be standard extensions of<span> </span><a
class="twikiLink"
href="https://wiki.ivoa.net/twiki/bin/view/IVOA/ObsCore"
style="text-decoration: none; color: rgb(69, 113, 208); background-color: transparent; border-color: rgb(69, 113, 208); border-style: none none dotted; border-width: 1px;">ObsCore</a><span> </span>but
could live outside the<span> </span><a class="twikiLink"
href="https://wiki.ivoa.net/twiki/bin/view/IVOA/ObsCore"
style="text-decoration: none; color: rgb(69, 113, 208); background-color: transparent; border-color: rgb(69, 113, 208); border-style: none none dotted; border-width: 1px;">ObsCore</a><span> </span>standard
itself if you catch my drift.</p>
<p
style="margin: 1em 0px 0px; background-color: rgb(255, 255, 255); color: rgb(0, 0, 0); font-family: arial, verdana, sans-serif; font-size: 13.65px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: left; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">-
Very much related to that, columns like
instrument_and_diameter, instrument_ant_number, or almost all
instrument_ant_* for that matter, are, for any array of radio
receivers unhelpful. I have argued before. In my opinion
they'd fall under an instrument characterisation. I'm also
thinking of dipole or large-N-small-D arrays here, in the
event they'd want to publish some visibility data.</p>
<p
style="margin: 1em 0px 0px; background-color: rgb(255, 255, 255); color: rgb(0, 0, 0); font-family: arial, verdana, sans-serif; font-size: 13.65px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: left; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">Possibily
a proper instrument characterisation mechanism can be thought
of, but in the end, only two things are important for
interoperability I think: what was the instrument signature at
the time of observation and has it been removed from the
published data.</p>
<p
style="margin: 1em 0px 0px; background-color: rgb(255, 255, 255); color: rgb(0, 0, 0); font-family: arial, verdana, sans-serif; font-size: 13.65px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: left; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">My
.02 arbitrary currency units, obviously.</p>
<p
style="margin: 1em 0px 0px; background-color: rgb(255, 255, 255); color: rgb(0, 0, 0); font-family: arial, verdana, sans-serif; font-size: 13.65px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: left; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;"><span
class="twikiNewLink"><a
href="https://wiki.ivoa.net/twiki/bin/edit/IVOA/MarjoleinVerkouter?topicparent=IVOA.ObsCoreExtensionForRadioData;nowysiwyg=0"
rel="nofollow"
title="MarjoleinVerkouter (this topic does not yet exist; you can create it)"
style="text-decoration: none; color: rgb(183, 53, 30); background-color: transparent; border-color: rgb(183, 53, 30); border-style: none none dotted; border-width: 1px;">MarjoleinVerkouter</a></span><span> </span>2023-12-18</p>
<p
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<br class="Apple-interchange-newline">
</blockquote>
</p>
<p>Humm, before ruling out all this, I just want to explain where it
came from. This was not a fantasy of the editor or first authors.</p>
<p>To help a user to discover quality data we have to give a way to
estimate this quality, by trying to characterize the original raw
data.</p>
<p>Of the course the uv plane characterization is the best we can
do, but if we cannot provide them whta can be done ? nothing ?</p>
<p>Our background was this rather old but very comprehensive note
by Anita Richards </p>
<p> <a class="moz-txt-link-freetext" href="https://wiki.ivoa.net/internal/IVOA/SiaInterface/Anita-InterferometryVO.pdf">https://wiki.ivoa.net/internal/IVOA/SiaInterface/Anita-InterferometryVO.pdf</a></p>
<p>The whole section 1.1 is to be read again.</p>
<p>But I would like to mention here these excerpts :</p>
<p>
<blockquote type="cite">Component telescope properties, such as
location and diameter, can be used to deduce other prop-<br>
erties if these are not provided explicitly. Should these be
included in this model or in Prove-<br>
nance/Observation (and/or a link to the array web page in the
absence of the latter models)</blockquote>
</p>
<p>and <br>
<blockquote type="cite">Diagnostics of the uv plane coverage.<br>
– Most conventional radio archives provide links to plots (such
as Fig. 1) of visibility am-<br>
plitude as a function of uv distance This is in dimensionless
units of (projected baseline<br>
length)/(observing wavelength), or SI multiples, written as e.g.
Mλ (mega-lambda).<br>
– Table 1.1 provides a machine-readable quantification of Fig.
1.<br>
– The range of the maximum and minimum uv distances present in a
data set is the simplest<br>
fairly accurate quantifier. The example shown in Table 1.1 gives
114.93–3553.52 kλ.<br>
<br>
– The range of intermediate spacings available as well as the
limits of uv coverage affect the data<br>
quality. There is no commonly-used universal quantifier for this
although the coverage could<br>
be described in more detail using the finer levels of
Characterization. Astronomers usually<br>
inspect plots such as Fig. 1 or the dirty beam (see Section 1.2
and Fig. 2). The time axis also<br>
provides some information, see below.<br>
<b>– A crude estimate of coverage can be obtained from the
number of participating telescopes,<br>
the maximum and minimum baselines on the ground in m or km and
the duration of the<br>
observation</b></blockquote>
(last item bolded by me)</p>
<p>So if the data provider is not able to quantifify the uv plane
quality some of these instrumental details seem to be useful</p>
<p>In addition, immediatly before we started the radio interest
group in the VO there was an Asterics project / ESCAPE project
initial work on that</p>
<p>which happened to be a first contribution.</p>
<p>A dedicated meeting on "radio astronomy data in the VO" was held
in Strasbourg in february 2019.</p>
<p>Several radio astronomers gave talks about their needs and
requirements for data discovery.<br>
</p>
<p>Loook at Katarina Lutz presentation here :<br>
</p>
<p><a class="moz-txt-link-freetext" href="https://www.asterics2020.eu/dokuwiki/lib/exe/fetch.php?media=open:wp4:wp4techforum5:talk_klutz.pdf">https://www.asterics2020.eu/dokuwiki/lib/exe/fetch.php?media=open:wp4:wp4techforum5:talk_klutz.pdf</a></p>
<p>or Yelena Stein's one <br>
</p>
<p><a class="moz-txt-link-freetext" href="https://www.asterics2020.eu/dokuwiki/lib/exe/fetch.php?media=open:wp4:voradio_stein_.pdf">https://www.asterics2020.eu/dokuwiki/lib/exe/fetch.php?media=open:wp4:voradio_stein_.pdf</a></p>
<p>I copy paste you two interesting slides (one from each of these
two talks) below</p>
<p>So my conclusion : I understand we still have to discuss the
details and science cases. But do not exclude instrumental and
configuration details</p>
<p>to early.</p>
<p>Cheers</p>
<p>François<br>
</p>
<p><img src="cid:part1.Y90p2Qoj.Xgnyu18b@astro.unistra.fr" alt=""></p>
<p><br>
</p>
<p><br>
</p>
<p><br>
</p>
<p><img src="cid:part2.EoRaIEzA.3NLr006E@astro.unistra.fr" alt=""></p>
<p><br>
</p>
<p><br>
</p>
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