[HEIG -Obscore extension ] Distributing observation data sets together with instrumental response functions

[Mireille Louys]

Hi HEIG ,

Since a while we have been discussing about the way Obscore can be used 
for the distribution and discovery of high energy data sets

in the context of multi-wavelength data discovery in the VO.

Obscore describes how  data products  are sampled along the main 
physical axes involved in astronomical data :

spatial, spectral, temporal, polarimetric.

Coverage, resolution and sampling properties are mandatory in the 
Obscore table to represent a dataset.
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 .

I think this rule does not fully apply for describing instrument 
response function as data sets .
The response functions belong to the instrumental/calibration 
information , and probably are stored in Calibration DB .
I think this is not homogeneous in content with the observation datasets 
representing flux variation on the sky,
so they should not be considered as Obscore data product type.

Currently from our HEIG discussions , we have identified two ways to 
distribute data sets in Obscore :

  * Include the data  together with their instrument response details
    into a tarball.
    this can be represented by a data product type like
    eventlist-bundle, spectrum-bundle, etc . depending of the axes
    covered in the data
  * 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.
    accessible through the datalink table .
    for instance , reusing  examples given by Laurent Michel
      o spectrum bundle

        a) If this spectrum bundle is exposed as an ObsCore entry in a
        data link, we should have something like this:

        Obscore row:
        -----------
        - dataproduct_type=spectrum-bundle (tbd)
        - access_format=application/x-votable+xml;content=datalink

        Datalink response:
        -----------------
        - link #1
           - semantics=#this
           - content_qualifier=spectrum-bundle (TBD)
           - content_type=application/tar+gzip
           - description="spectrum file + preview + ARF + RMF +
        Background spectrum"


        b) If the spectrum is exposed in a separate row:

        Obscore row:
        -----------
        - product_type=spectrum
        - access_format=application/x-votable+xml;content=datalink

        Datalink response:
        -----------------
        - link #1
           - semantics=#this
           - content_qualifier=spectrum
           - content_type=application/fits
           - description="spectrum file"
        - link #2
           - semantics=#package
           - content_qualifier=spectrum-bundle (TBD)
           - content_type=application/tar+gzip
           - description="spectrum file + preview + ARF + RMF +
        Background spectrum"

      o if we define the terms hierarchy as a response vocabulary like 
        ivoa.net/rdf/instrument-response
          + /Instrument_response/
              # /arf/
              # /rmf/
              # /energy-disp/
              # /background/
              # /etc./

      o from Bruno's example we can have :
          +

            Obscore row:
            -----------
            - product_type=spectrum-bundle
            - access_format=application/x-votable+xml;content=datalink

            Datalink response:
            -----------------
            - link #1
            - semantics=#this
            - content_qualifier=event-list
            - content_type=application/fits
            - description="event file"
            - link #2
            - semantics=#arf
            - content_qualifier=#arf
            - content_type=application/x-fits-ogip (to be added in table
            1 of ObsCore)
            - description="ARF "
            - link #3
            - semantics=#rmf
            - content_qualifier=#rmf
            - content_type=application/x-fits-ogip (to be added in table
            1 of ObsCore)
            - description="RMF"
            - link #4
            - semantics=#background
            - content_qualifier=image ( if it is a map)
            - content_type=application/x-fits-ogip (to be added in table
            1 of ObsCore)
            - description="Background"

            doing so , we can discover a data set based on the Obscore +
            heig extension columns ,
            and in a second step access the response files stored in the
            calibration part of an archive through the links .

Comments, examples, ideas?

Mireille

-- 
--
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
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.ivoa.net/pipermail/dm/attachments/20250523/52dd8644/attachment.htm>