[Heig] Post running meeting thoughts

[BONNAREL FRANCOIS gmail]

Dear all,

After the meeting last week, I was still thinking about what the Chandra 
prototype could look like

For the Paris HESS prototype, I get the idea since a couple of years now.

Trying to understand what the CSC data products could be I came back to 
Ian's Malta interop presentation.

I copy/paste here one of the slides where some of these products are 
described.

Before trying to define dataproduct_type vocabulary terms for those 
products I am wondering if we really need to expose all this data 
directly in

an ObsTAP service.

For example background images, psf, pixel mask, bad pixel regions, ARF 
belong to the "response functions" category if I'm not mistaking.

They probably are attached to a photon event list or an image or ....

Including all this in the main ObsCore table will overload it very 
heterogeneously. Some of these response functions will be similar to 
what we get in other domains (psf) some will be very different and 
specific to Xray.

I understood that the spatial, spectral, time characterization of these 
specific products could be borrowed from the observation they are 
associated with. It's ok but is that useful ?

For accessing these response functions I can imagine 4 solutions which 
all will have the  advantage to let the OBsTAp service be focused on 
measurements obtained from the sky at whatever calib level.

     1 ) the photon event list and response functions are gathered 
together in the same tar or archive file (or MEF) which is typed as an 
event-bundle. Direct access to this bundle from Obstap access_url is 
then easy. It's the client task to figure out what to do with the 
content of the bundle.

    2 ) the various response material is kept as a set of individual 
products. All are associated to an event list or an image or a spectrum. 
In that case ObsTAP point to a datalink response which lists all these 
different products. The semantics FIELD writes calibration or response 
function.  Content_qalifier FIELD writes the very nature of the product.

    3 ) the DataLink reponse content may be organized as a TAP table. 
It's then possible to query at the same time the  ObsTAP table and the 
DataLink-like table by a join on ObsCore/obs_publisher_did-DataLink/ID

   4 ) if we need a more detailed description of the response products 
to help discover and select them we could imagine creating a specific 
"response product" table following a specific datamodel as proposed by 
Mireille in her Gorlitz presentation. This will allow to attach specific 
eg :

       - time range to a psf or

       - specific release date and description to an arf or a bad pixel map

       -....

       Natural join on obs_publisher_did in both tables will allow to 
query those table at the same time with selection criteria from both.

    Cheers

François



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