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<p>Hi HEIG ,</p>
<p>Since a while we have been discussing about the way Obscore can
be used for the distribution and discovery of high energy data
sets <br>
</p>
<p>in the context of multi-wavelength data discovery in the VO.</p>
<p>Obscore describes how data products are sampled along the main
physical axes involved in astronomical data : </p>
<p>spatial, spectral, temporal, polarimetric.</p>
<p>Coverage, resolution and sampling properties are mandatory in the
Obscore table to represent a dataset. <br>
this means we need to have s_ra, s_dec, em_min, em_max , t_min,
t_max, s_region, s_resolution, etc. filled with representative
values .<br>
</p>
<p>I think this rule does not fully apply for describing instrument
response function as data sets .<br>
The response functions belong to the instrumental/calibration
information , and probably are stored in Calibration DB . <br>
I think this is not homogeneous in content with the observation
datasets representing flux variation on the sky, <br>
so they should not be considered as Obscore data product type. <br>
</p>
<p>Currently from our HEIG discussions , we have identified two ways
to distribute data sets in Obscore : <br>
</p>
<ul>
<li>Include the data together with their instrument response
details into a tarball.<br>
this can be represented by a data product type like
eventlist-bundle, spectrum-bundle, etc . depending of the axes
covered in the data</li>
<li>Distribute the data set as a datalink entry which contains a
list of links to the dataset , e.g an event-list and to the
various instrumental response files, arf rmf, psf, energy
dispersion , etc.<br>
accessible through the datalink table .<br>
for instance , reusing examples given by Laurent Michel <br>
</li>
<ul>
<li>spectrum bundle <br>
<br>
a) If this spectrum bundle is exposed as an ObsCore entry in a
data link, we should have something like this: <br>
<br>
Obscore row: <br>
----------- <br>
- dataproduct_type=spectrum-bundle (tbd) <br>
- access_format=application/x-votable+xml;content=datalink <br>
<br>
Datalink response: <br>
----------------- <br>
- link #1 <br>
- semantics=#this <br>
- content_qualifier=spectrum-bundle (TBD) <br>
- content_type=application/tar+gzip <br>
- description="spectrum file + preview + ARF + RMF +
Background spectrum" <br>
<br>
<br>
b) If the spectrum is exposed in a separate row: <br>
<br>
Obscore row: <br>
----------- <br>
- product_type=spectrum <br>
- access_format=application/x-votable+xml;content=datalink <br>
<br>
Datalink response: <br>
----------------- <br>
- link #1 <br>
- semantics=#this <br>
- content_qualifier=spectrum <br>
- content_type=application/fits <br>
- description="spectrum file" <br>
- link #2 <br>
- semantics=#package <br>
- content_qualifier=spectrum-bundle (TBD) <br>
- content_type=application/tar+gzip <br>
- description="spectrum file + preview + ARF + RMF +
Background spectrum" <br>
<br>
</li>
<li>if we define the terms hierarchy as a response vocabulary
like ivoa.net/rdf/instrument-response<br>
</li>
<ul>
<li><i>Instrument_response</i></li>
<ul>
<li><i>arf</i></li>
<li><i>rmf</i></li>
<li><i>energy-disp</i></li>
<li><i>background</i></li>
<li><i>etc.</i><br>
<br>
</li>
</ul>
</ul>
<li>from Bruno's example we can have : <br>
</li>
<ul>
<li>
<p>Obscore row:<br>
-----------<br>
- product_type=spectrum-bundle<br>
- access_format=application/x-votable+xml;content=datalink<br>
<br>
Datalink response:<br>
-----------------<br>
- link #1<br>
- semantics=#this<br>
- content_qualifier=event-list<br>
- content_type=application/fits<br>
- description="event file"<br>
- link #2<br>
- semantics=#arf<br>
- content_qualifier=#arf <br>
- content_type=application/x-fits-ogip (to be added in
table 1 of ObsCore)<br>
- description="ARF "<br>
- link #3<br>
- semantics=#rmf<br>
- content_qualifier=#rmf <br>
- content_type=application/x-fits-ogip (to be added in
table 1 of ObsCore)<br>
- description="RMF"<br>
- link #4<br>
- semantics=#background<br>
- content_qualifier=image ( if it is a map)<br>
- content_type=application/x-fits-ogip (to be added in
table 1 of ObsCore)<br>
- description="Background" </p>
<p>doing so , we can discover a data set based on the
Obscore + heig extension columns , <br>
and in a second step access the response files stored in
the calibration part of an archive through the links . <br>
</p>
</li>
</ul>
</ul>
</ul>
<p>Comments, examples, ideas? <br>
</p>
<p>Mireille<br>
</p>
<pre class="moz-signature" cols="72">--
--
Mireille Louys, MCF (Assistant Professor)
Centre de données Astronomiques (CDS) Equipe Images, 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</pre>
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