ObsCore: o_ucd for uncalibrated data?

[Petr Skoda]

>
> ADU’s are not fluxes (ADU/s/pix^2 might be) but simply uncalibrated 
> counts, so I’d go with
>
> 	phot.count;stat.uncalib
>
> However, “phot” means “photometry”, not “photons”, and ADU’s are just a 
> different unit of photometric counting, so
>
> 	phot.count
>
> (some number of photometric events) wouldn’t be so bad after all.  More 
> metadata is usually better, but one has to stop somewhere….

>
> RIck

>>> phot.count represents the number of photons counted
>>> by the instrument, while what I'm talking about is
>>> really instrumental data numbers (ADUs) which are far
>>> from being the number of photons.

NO I think its a bad interpretation - I understand the UCD exactly as 
presented by Frederic

in http://www.ivoa.net/documents/REC/UCD/UCDlist-20070402.html

is said
E | phot.count            | Flux expressed in counts

unlike

E | phot.flux                                        | Photon flux

what does this mean ?     number of photons per second ?


the term flux is well shaky as (in rigorous terms ) the flux is something 
per time but IMHO most people still understand the real meaning - BTW in 
VO lingua everything on vertical axis is FLUX (FluxAxis is synonymum for 
the measured variable axis evrywhere)

But the key is that it is not said "the flux expressed in photon 
counts.... - i.e. number of photons)

But if the UCD vocabulary would allow phot.ADU it would me more easier to 
express all RAW data .....

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*  Petr Skoda                         Phone : +420-323-649201, ext. 361 *
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