VEP6: blurry definition for the term #calibration

[Mireille LOUYS]

Dear Semantics,

I have comments about in the last VEP for calibration , here :http://volute.g-vo.org/svn/trunk/projects/semantics/veps/VEP-006.txt  <http://volute.g-vo.org/svn/trunk/projects/semantics/veps/VEP-006.txt>

Vocabulary: http://www.ivoa.net/rdf/datalink/core
Author: Markus Demleitner <msdemlei at ari.uni-heidelberg.de>
Date: 2020-09-09

Term: #calibration
Action: Modificiation
Description: Data products that can be used to remove instrumental
   signatures from #this.

I agree with this first sentence.
I suggest we could even say : "Data products relevant to remove instrumental signatures from #this."

I disagree with the/two following sentences/  here below:
///Note that the calibration steps such data products feed have not been 
applied to #this yet. ////To link calibration data already reflected in #this, use #progenitor./

In my understanding, when a dataset is tagged as calibration, this has nothing to do with the fact it*has been*  applied or it*is recommended to apply *on the dataset in consideration:/#this /
How should I name the datalink semantic tag when I link a PSF dataset to an observation datafile which was used and applied already ?
In case I have 10 progenitors , I don't want to have to sort between all #progenitor-tagged datasets to be able to find which is the PSF one, used for calibration.

Example for merging IFU data cube:
I consider a cube ( 2D+lambda) obtained in a Fusion (recombination) operated on 10 observed cubes. The Fusion uses a PSF cube as calibration within the process. This PSF's version and properties are important to evaluate the quality of the fusion operation and the final merged data product.
In this case I would like to distinguish the two categories:
final-merged cube
	linked via #progenitor :C1, ... C10
	linked via #calibration: PSFCube
Some fusion processing could also use 50 cubes, or more.

One more reason :
#progenitor should be reserved to designate the data in transformation through various steps within a pipeline.
this applies to the data stream...
calibration, configuration, parameter sets have a distinct nature with respect to the data processing.
The two categories should not be mixed, in my view.

Summary:
#calibration is not linked to the temporal aspect, life of a dataset.
I see it as a contribution for the astronomer to evaluate the pertinence of a discovered data set with respect to scientific criteria.

I hope this help to clarify the confusion between #progenitor and #calibration.

Best wishes , Mireille

-- 
--
Mireille Louys,  MCF (Associate Professor)
Centre de données CDS		IPSEO, Images, Laboratoire Icube
Observatoire de Strasbourg	Telecom Physique Strasbourg
11 rue de l'Université		300, Bd Sebastien Brandt CS 10413
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Tel: +33 3 68 85 24 34

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