ObsCore: o_ucd for uncalibrated data?

[Alberto Micol]

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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