[Observation] relation to Dataset

[Arnold Rots]

If multiple observations have to be taken care of through provenance,
then why should a single observation not be handled the same way?
Don't get me wrong: I think neither should be handled through provenance.

Examples are: VLA multi-configuration images; stacked images;
multi-observation event files.

It is much clearer and more intuitive if we just simply allow a Dataset
to be associated with multiple Observations.
Actually, I think this is absolutely a requirement.

  - Arnold

-------------------------------------------------------------------------------------------------------------
Arnold H. Rots                                          Chandra X-ray
Science Center
Smithsonian Astrophysical Observatory                   tel:  +1 617 496
7701
60 Garden Street, MS 67                                      fax:  +1 617
495 7356
Cambridge, MA 02138
arots at cfa.harvard.edu
USA
http://hea-www.harvard.edu/~arots/
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On Thu, Nov 14, 2013 at 6:29 PM, Douglas Tody <dtody at nrao.edu> wrote:

> On Thu, 14 Nov 2013, Arnold Rots wrote:
>
>  From this description I am beginning to suspect that a Dataset can be
>>>
>> derived from
>> (associated with) no more than one Observation.
>> That seems utterly wrong; multiple Observations can be combined into a
>> single Dataset.
>> Or did I misunderstand?
>>
>
> Multiple Observations can be and often are combined to produce a new
> Dataset, however describing that history would be likely be the
> responsibility of the Provenance model.  At the level of Observation it
> would probably be a new "Observation" (or at least Dataset).  Depends
> upon how strict we are with the concept of Observation.  The
> CreationType and calibration level say something about it being a
> synthesized/derived data product.
>
>
>  I think it is OK to require that a Dataset is associated with at least one
>> Observation,
>> provided that a model or simulation can be described as an Observation.
>>
>
> In practice that is what we are doing, to keep things simple; DataSource
> can be something like "theory".
>
>         - Doug
>
>
>  Cheers,
>>
>>  - Arnold
>>
>> ------------------------------------------------------------
>> -------------------------------------------------
>> Arnold H. Rots                                          Chandra X-ray
>> Science Center
>> Smithsonian Astrophysical Observatory                   tel:  +1 617 496
>> 7701
>> 60 Garden Street, MS 67                                      fax:  +1 617
>> 495 7356
>> Cambridge, MA 02138
>> arots at cfa.harvard.edu
>> USA
>> http://hea-www.harvard.edu/~arots/
>> ------------------------------------------------------------
>> --------------------------------------------------
>>
>>
>>
>> On Thu, Nov 14, 2013 at 12:08 PM, CresitelloDittmar, Mark <
>> mdittmar at cfa.harvard.edu> wrote:
>>
>>  All,
>>>   This thread is for discussion on the relation between Observation and
>>> Dataset.
>>>
>>> ref: ObsCoreDM - http://www.ivoa.net/documents/
>>> ObsCore/20111028/index.html
>>> ref: diagram illustrating relation of Image/Spectral Observation to
>>> ObsCoreDM (draft)
>>>
>>> http://www.ivoa.net/pipermail/dm/attachments/20131113/
>>> c9ef7581/attachment-0001.png
>>>
>>> motivation
>>>   It is clear that there is a relationship between "Observation" and a
>>> more generic "Dataset".  This "Dataset" would contain elements such as
>>> the
>>> dataProductType, and dataProductSubtype, presumably others.  This object
>>> has not been formally defined.
>>>
>>>   In ObsCore, there is an implied relationship for Observation as an
>>> Extension of Dataset in the location of these attributes.  So, I have
>>> always interpreted that Observation "is" a Dataset.  This is reflected in
>>> my choice of the name "ObservationDataset" in the left hand package of my
>>> diagram.  It implies that it is a Dataset extended for Observation
>>> purposes.
>>>
>>>   Recent discussion brings this relationship into question, with
>>> assertions that an Observation can be associated with 0 or more Datasets.
>>>
>>>   This has real ramifications for the Image and Spectral models..
>>>
>>> Seed:
>>>
>>> If the relation is Observation "has" 0..* Dataset, then all the diagrams
>>> to date are wrong.
>>> It feels like this would be a fundamental change to all these models.
>>>
>>>   - there would need to be a bi-directional relation between Observation
>>> and Dataset
>>>        (observation has 0..* Dataset; Dataset associated with 1
>>> Observation)
>>>     Hmm.. since there can be Datasets not associated with Observations,
>>> this would
>>>     need to be a specialization of Dataset.. (ObservationDataset.. but
>>> not
>>> the one in my diag.)
>>>
>>>   - the Char associated with Observation would characterize the total
>>> space of all included Datasets.  (0..1) relation to Observation.  If no
>>> Datasets, no Char
>>>
>>>   - each Dataset would require it's own Characterisation, specific to
>>> it's
>>> space.
>>>     (so there is another attribute for Dataset).
>>>
>>>   - we would need to specify which of the elements are associated to the
>>> Dataset, and which to the Observation.  e.g. DataModel => Dataset;
>>>  Target
>>> => Observation
>>>
>>> Thoughts?
>>> Mark
>>>
>>>
>>>
>>>
>>
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