HEIG_23Sep14 < IVOA

IVOA Web>IvoaSciencePriorities>HEGroup>HEIG_23Sep14 (2023-09-15, JanetEvans) (raw view)
---+ HEIG Meeting (online) - Thu, Sep 14 2023 @ 13:00 UTC

%TOC%

   * _Attendees_ :
      * Mark Cresitello-Dittmar, Mathieu Servillat, Catherine Boisson, Francois Bonnarel, Raffaelle D'Abrusco, Ian Evans, Janet Evans, Matthias Fuessling, Tess Jaffe, Bruno Khelifi, Mireille Louys, Jutta Schinabel, Fabian Schussler
   * _Regrets_ :
      * Ada Nebot
---++ <a name="Zoom"></a>Zoom
---++ <a name="Actions"></a>Actions
   * JE: Send doodle poll for a mtg in ~1 month (Oct 19 @13:00 was a possibility; Oct 11 bad)
   * CTAO: prepare a presentation/discussion on Instrument Response Function (IRF) data and how it relates to the event data (for next mtg)
   * IE: Prepare a presentation/discussion on ARF & RMF and how it relates (for next mtg)
   * DM project leads: Make an event list & supporting products available to the group to review; try to map that data to the Cube model using the Chandra example Mark presented
   * Mark CD: Follow up with a group or 2 to review their data and model - offer input and also take in possible changes to current cube thinking
   * Mathieu: What makes an event list unique? ie: What content should users expect to exist in an Event List instance? Let's try to answer that at the next mtg
   * All: Plan for side meeting at the next interop in Nov - hybrid
---++ <a name="Meeting Notes"></a>Meeting Notes

   * MCD presentation of the IVOA Dataset & Cube model and as an example, the Chandra event list mapping to the model
   * Q&A Highlights: Good discussion and participation overall
      * General discussion that the model can map to specific event lists for each project - let's try the exercise and see if we're missing something??
         * BK: event lists containing time, energy, direction
         * BK: why a separation of !Image and !SparseCube?
            * MCD: They are structurally different, !NDImage contains pixel axes, while the !SparseCube is a collection of Points. They both share the same !DataAxis elements in the model, so interaction/combination should be possible. We will need to see the example.
            * Variable size bins?? - yes
            * FB: it may be possible to describe a !DataProduct with some sparse and some binned axes as a !SparseCube with a !DataAxis of !NDImage type.
         * ...
      * Discussion on !Dataset (header info) & !DataProduct (the Data itself) & use of those terms in the model
         * MCD: there are somewhat contradictory statements in the current model which stem from conflating the concept of !Dataset as a modeled object and the serialization of that object.
            * !Dataset is only the metadata
            * a dataset may be a single file (eg: Image, Spectrum), or a tar file or directory containing multiple files
         * MS: at CTA, the !DataProduct is considered to contain both the metadata, and data.
         * This topic can be discussed more, perhaps in the DM group with a goal to find concensus on names and relations between 3 objects
            * The collection of metadata: currently Dataset
            * The structural definition of the data: currently DataProduct
            * The container holding both: currently not modeled.
      * Discussion on Supporting products and how they fit in (IRF, ARF, RMF) - examples for next mtg
         * BK: we need to include the instrument response function, it is very important to the interpretation of the event list
            * IE: described how Chandra uses a rather simple IRF and performs the conversion from PHA to Energy during processing, storing energy as a static column.
            * MCD: possibly can use Transform
               * IE: asserted that the process for the conversion is rather complex, and further requires Spectra.. so may not be well suited for Transform.
            * TJ: notes that HEASAR standards for Spectra require a 'channel' axis.. is this supported
               * IE: the Chandra pha/pi columns are equivalent to channel
            * BK: for them, the relation between IRF and is much looser.. may be 1-1 with an event list or 1-* (or *-1 ?.. I (MCD) don't remember what was said exactly).
         * TJ: question if the model has been compared against the OGIP standard in full
            * MCD: Work to date has focused on the Chandra event list example, Ian says Chandra meets the OGIP standard. We should review OGIP more generally and a HEASARC example.
               * post-meeting side note: if we map an OGIP standard to the Cube model, then any implementation which understands an OGIP compliant serialization is a Cube model implementation.
      * MS: Raised Question - What are the key Measurements expected in High Energy Event Lists? eg: Time, Position, Energy
         * Further discussion for next mtg
      * MCD: Raised Question - Do our various event lists include errors?
         * BK: have optional error elements
         * JS: neutrino data has positional errors usually, sometimes energy
      * Other questions/topics raised in the presentation not yet discussed.
         * We need to refine modeling of non-measurement types of data from example products (eg: quality bits)
         * Do we need to model the concept of 'data subspace'.. for Chandra, the GTIs are a component of this concept as are any REGION filters applied to the event list.
         * Do we need to support virtual data in version 1?
            * this was not discussed, but the content of the general discussion leads me to believe that this is needed.

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Topic revision: r4 - 2023-09-15 - JanetEvans
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