Comments on other ObsCore parameters : o_ucd (From Alessandra Vincenzo and Marco)

[Bonnarel]

From Alessandra Vincenzo and Marco

o_ucd In the current UCD vocabulary (UCD1+ Controlled Vocabulary 1.4 https://ivoa.net/documents/UCD1+/20210616/index.html) there appear to be no primary words suitable to describe raw single dish radio data. For pulsar data and transient radio data, o_ucd=stat.Fourier could be used, as proposed for visibility data in the Obscore extension for radio data document (v 1.0). The use of o_ucd=phot.flux.density for raw single dish data does not seem appropriate, since the single dish measured quantity is expressed in raw counts. These counts come from the digitisation of a voltage signal generated in the receiver chain by the incoming electromagnetic field.

[Bonnarel]

From Alessandra Vincenzo and Marco The use of o_ucd=phot.flux.density for raw single dish data does not seem appropriate, since the single dish measured quantity is expressed in raw counts. These counts come from the digitisation of a voltage signal generated in the receiver chain by the incoming electromagnetic field.

From François Bonnarel :

there is phot.count : wouldn't that be ok for raw single dish data ?

[Bonnarel]

From Alessandra Vincenzo and Marco The use of o_ucd=phot.flux.density for raw single dish data does not seem appropriate, since the single dish measured quantity is expressed in raw counts. These counts come from the digitisation of a voltage signal generated in the receiver chain by the incoming electromagnetic field.

From François Bonnarel :

there is phot.count : wouldn't that be ok for raw single dish data ?

From Marco Molinaro : I think it doesn't because it's not photons that are recorded by the ADC conversion of the EM field. This looks semantically different. But I need @alessandra.zanichelli@inaf.it to check if my comment is right.

[Bonnarel]

From Alessandra Vincenzo and Marco The use of o_ucd=phot.flux.density for raw single dish data does not seem appropriate, since the single dish measured quantity is expressed in raw counts. These counts come from the digitisation of a voltage signal generated in the receiver chain by the incoming electromagnetic field.

From François Bonnarel : there is phot.count : wouldn't that be ok for raw single dish data ?

From Marco Molinaro : I think it doesn't because it's not photons that are recorded by the ADC conversion of the EM field. This looks semantically different. But I need @alessandra.zanichelli@inaf.it to check if my comment is right.

From Baptiste Cecconi : there might indeed be some semantics issue here. We had this discusssion a few years ago in the Semantics WG, and the proposed solution was to use "phot.flux.density" for both photometric flux density and EM wave flux density, since there would be no sense to have 2 terms in this case. I would say that the raw counts issue is different: "phot.count" means "Flux expressed in counts" (and this is really counting photon hits), whereas the output of an RF ADC is not photon hit counts. I'm submitting a new term for ADU (i.e., analogue to digital converter units) to the UCD group.

[Bonnarel]

This has probably to be discussed with request by Markus Dolensky :

Can somebody suggest a UCD for complex voltage data, please?

Context is the Obscore o_ucd for PSRFITS data.

[Bonnarel]

Discussion still going on in the UCD group