ObsCore: o_ucd for uncalibrated data?

[Marco Molinaro]

Hi Alberto,
not an expert on this, but would

phot.flux;stat.uncalib

fit your case?
I added Semantics to the reply, just in case some relevant people were
not on the dm list.

Cheers,
    Marco


2015-07-24 16:35 GMT+02:00 Alberto Micol <amicol.ivoa at googlemail.com>:
>
> Thanks Petr,
>
> Unforunately phot.count does not seem correct...
> 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.
>
> That is, I cannot take the number of ADUs, multiply
> it by the energy of a photon (which I can derive from the wavelength info
> of obscore) to get a representative flux...
>
> That is why I would like to have a phot.uncalibrated,
> or phot.adu, or similar... any other idea?
>
> Thanks,
> Alberto
>
> On 24 Jul 2015, at 16:17, Petr Skoda wrote:
>
> On Wed, 22 Jul 2015, Alberto Micol wrote:
>
>
> Dear ObsCorers,
>
>
> At ESO we are serving spectra very well calibrated in wavelength, but
> uncalibrated in flux.
>
> What would be the correct o_ucd value for such data?
>
> I cannot find a UCD that could fit… something like: phot.uncalibrated would
> be nice to have…
>
> Any idea?
>
>
> Hi Alberto,
>
> In stellar astronomy we formally describe the vertical axis as integrated
> flux in ADU or counts ....
> It is in principle produced by summing all pixels values in given wavelength
> but modified by various sensitivies of detetror (flat-field etc) . So
> perhaps something like flux in counts may be used??
> So UCD="phot.count"
> ?????
>
>
> Than the problem comes with continuum normalization made by some pipelines.
> For this was already a suggestion by Mirellei for SDM
>
> Char.FluxAxis.CalibrationStatus='NORMALIZED'
> Char.FluxAxis.unit=NULL  or 'unitless'
> Char.FluxAxis.ucd=phot.flux;arith.ratio;
>
>
> Is there any other suggestion ?
>
> Just my practical view for intended usage of obscore:  I am either
> interested in getting SOME form of spectra of my object - so I am perfectly
> happy with the RAW extracted spectrum - in counts (or ADUs) or in a SPECIFIC
> form for analysis - than I prefer the FLUXCALIB=normalized or ABSOLUTE - if
> I already know about many spectra of the same object in given form. But more
> flexible approarch is to use DataLink.
>
>
> OTOH - it is not sometimes obvious the spectra are normalized to continum
> without visual inspection - you see the most values are at level 1.0 and
> there is not visible skew of the spectra ....
>
> BTW - I am glad that the ESO is still considering the VO as a viable
> technology for presenting data ....
>
> *************************************************************************
> *  Petr Skoda                         Phone : +420-323-649201, ext. 361 *
> *  Stellar Department                         +420-323-620361           *
> *  Astronomical Institute AS CR       Fax   : +420-323-620250           *
> *  251 65 Ondrejov                    e-mail: skoda at sunstel.asu.cas.cz  *
> *  Czech Republic                                                       *
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>
>