SDM evolution roadmap: Data.FluxAxis.Accuracy.LowerLimit another UCD suggestion

[Salgado, Jesus]

Just to comment that it also depends on the definition of these upper/lower limits

The UCDs proposed are in line with an Upper detection limit, Lower detection limit at instrument level but, at least in high-energy, the Upper Limit is usually the minimum number of counts from a source necessary for a detection (or in flux space) so the Upper Limit would be more related to the instr.sensitivity;phot.flux.

So,  are we talking about the upper/lower limits of the instrument or the source? Both are related but the interpretation is different

Cheers,
Jesús Salgado 
SKA Regional Centre Architect
jesus.salgado at skao.int
www.skao.int <https://www.skao.int/>
SKA Observatory
Jodrell Bank, Lower Withington,
Macclesfield, SK11 9FT, UK
 

On 28/07/2022, 09:51, "Salgado, Jesus" <jesus.salgado at skao.int> wrote:

    Dear all,

    I fully agree that Upper/Lower Limits are not errors so, I think, it should not be treated as such from the ontology point of view.
    I think we could use both ideas and separate the concepts of Upper and Lower Limits.

    For me, intuitively:
    Upper Limit is -> instr.saturation;phot.flux
    Lower Limit is -> instr.sensitivity;phot.flux

    (just removing the stat qualifiers)

    Cheers,
    Jesús Salgado 
    SKA Regional Centre Architect
    jesus.salgado at skao.int
    www.skao.int <https://www.skao.int/>
    SKA Observatory
    Jodrell Bank, Lower Withington,
    Macclesfield, SK11 9FT, UK


    On 28/07/2022, 07:41, "dm on behalf of Laurent Michel" <dm-bounces at ivoa.net on behalf of laurent.michel at astro.unistra.fr> wrote:

        Hello

        AS questioned by Mark Upper/Lower limits are not Error terms. There are detection thresholds.

        UpperLimit: If it was a source here it would have a flux below the upper limit
        - instr.sensitivity;phot.flux;stat.max ??

        Lower limit: If it was a source here it would have a flux above the lower limit
        - instr.sensitivity;phot.flux;stat.min ??

        Laurent


        Le 27/07/2022 à 17:10, CresitelloDittmar, Mark a écrit :
        > Thanks Mireille,
        > 
        > These are very similar to the current placeholders ( which mimic the StatErrorLow|High element ucds )
        > The main question I have about this was/is:
        >    o is LowerLimit/UpperLimit conceptually considered an Error term?
        > If not, then perhaps the detection limit options are more appropriate.
        > 
        > Mark
        > 
        > 
        > 
        > On Tue, Jul 26, 2022 at 11:40 AM Mireille LOUYS <mireille.louys at unistra.fr <mailto:mireille.louys at unistra.fr>> wrote:
        > 
        >     Dear dmers,
        > 
        >     just on the UCD assignation , I have another suggestion for /Data.FluxAxis.Accuracy.LowerLimit /
        >     which also validates in the UCD builder tool (http://cdsweb.u-strasbg.fr/UCD/cgi-bin/descr2ucd
        >     <http://cdsweb.u-strasbg.fr/UCD/cgi-bin/descr2ucd> ) and contains the flux information:
        >     stat.error;phot.flux;stat.min
        > 
        >     /Data.FluxAxis.Accuracy.UpperLimit/ whould also have this UCD
        >     stat.error;phot.flux;stat.max
        > 
        >     Thanks , Mireille,
        >     for the UCD maintenance committee.
        > 
        > 
        >     Le 21/07/2022 à 20:22, CresitelloDittmar, Mark a écrit :
        >>     Hi,
        >>
        >>     Follow-up on the UCD topic.  I've started a new Issue in the repository
        >>     <https://github.com/ivoa-std/SpectrumDM/issues/5> for this, so it can be worked outside of the structural model changes.
        >>     The primary objective is to select the proper terms for the new elements.. I'm not sure if we need to go outside this list
        >>     for that, but I'm hoping Vandana and Petr can get some review on this and provide feedback.
        >>
        >>     The following shows the UCDs put into this PR, and the suggested values per the UCD Builder utility.
        >>
        >>       * Data.SpectralAxis.order => "instr.order"
        >>       * Data.SpectralAxis.relorder => "instr.order"
        >>           o UCD builder suggests: "stat.variance;instr.order" for both, though "instr.order" can stand on its own.
        >>       * Data.FluxAxis.Accuracy.LowerLimit => "stat.error.phot.flux.density;em.*;stat.min" (Same as StatErrorLow)
        >>           o UCD builder suggests:
        >>               + "statistical lower limit" -> "stat.value;stat.min"
        >>               + "detection lower limit" -> "instr.saturation;stat.min"
        >>       * Data.FluxAxis.Accuracy.UpperLimit => "stat.error.phot.flux.density;em.*;stat.max" (Same as StatErrorHigh)
        >>           o UCD builder suggests:
        >>               + "statistical upper limit" -> "stat.value;stat.max"
        >>               + "detection upper limit" -> "instr.saturation;stat.max"
        >>
        >>
        >>     Mark
        > 
        >     -- 
        >     --
        >     Mireille Louys,  MCF (Associate Professor)
        >     Centre de données CDS		IPSEO, Images, Laboratoire Icube
        >     Observatoire de Strasbourg	Telecom Physique Strasbourg
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        > 

        --
        English version: https: //www.deepl.com/translator
        -- 
        jesuischarlie/Tunis/Paris/Bruxelles/Berlin

        Laurent Michel
        SSC XMM-Newton
        Tél : +33 (0)3 68 85 24 37
        Fax : +33 (0)3 )3 68 85 24 32
        Université de Strasbourg <http://www.unistra.fr>
        Observatoire Astronomique
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        F - 67200 Strasbourg

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