UCD problem in SSA/SpectrumDM

[Alberto Micol]

Dear All,

About 2.5 months ago I asked a question regarding a wrong UCD:

"How easy would it be to amend the SSA doc?"

I got an exhaustive answer to _that_ question.

I hence decided to read the book:
"The Art of Posing the Right Question"

After such interesting reading, I've learnt the lesson.

Alberto

:-D



On 20 Nov 2009, at 12:59, Alberto Micol wrote:

>
> Dear DAL chair,
>
> I'd like to mention a little but annoying problem with
> the instrument bandpass as defined in:
>
> - Spectrum DM
> - SSA v1.04
> - ssap-keywords.xls
>
> (see below all references in those documents to the instr.bandpass  
> UCD)
>
>
> The problem is that the the wrong UCD is assigned to the central  
> wavelength of the bandpass.
>
> All documents mention the UCD "instr.bandpass" for the field  
> identified by utype:
> Char.SpectralAxis.Coverage.Location.Value
>
> This is wrong because the central wavelength of a bandpass is a  
> wavelength, not a bandpass.
> The correct UCD should therefore be:
>
> em.wl.central;instr.bandpass
>
>
> and not just instr.bandpass.
>
>
> How easy would be to ammend the SSA document with such an easy change?
>
>
> (Without going into too many details, the fact that instr.bandpass  
> is instead used
> for a numeric field (central wavelength) makes the SSA validator  
> fail the test
> for the ESO SSA service, but that is a different issue that I will  
> address within
> a different forum. The problem here is that a wrong UCD is used.).
>
> Many thanks,
>
> Alberto
>
> PS: All references to instr.bandpass in the mentioned documents:
>
>
> Appendix D: SSA Data Model Summary:
> -----------------------------------
>
> DataID.Bandpass | instr.bandpass | Band as in RSM Coverage.Spectral  
> | char | * |
> Char.SpectralAxis.Coverage.Location.Value  |  instr.bandpass |   
> Spectral coord value |  double *** wrong UCD
> Char.SpectralAxis.Coverage.Bounds.Extent   | instr.bandwidth   |  
> Width of spectrum |  double
>
>
> IVOA Spectral Data Model:
> -------------------------
>
> Spectrum.DataID.Bandpass | instr.bandpass | Band, consistent with  
> RSM Coverage.Spectral | OPT | UNKNOWN |
> Spectrum.Char.SpectralAxis.Coverage.Location.Value | instr.bandpass  
> | Spectral coord value | MAN |
> <PARAM ID="SpectralLocation" datatype="double"  
> name="SpectralLocation" ucd="instr.bandpass"  
> utype="spec:Spectrum.Char.SpectralAxis.Coverage.Location.Value"
> value="6515.408759029946">
>
>
>
> ssap-keywords.xls spreadsheet:
> ------------------------------
>
> Bandpass         Spectrum.DataID.Bandpass  instr.bandpass  Band as  
> in RSM Coverage.Spectral   SPECBAND  char * q                    
> SpectralLocation Spectrum.Char.SpectralAxis.Coverage.Location.Value   
> instr.bandpass  Spectral coord value    SPEC_VAL         
> double           m    q
>
>
> -- 
> Alberto Micol
> Telephone: +49 89 32006 261
> Fax:       +49 89 32006 898
> Virtual Observatory Standards Group Lead
> Virtual Observatory Project Office
> Data Management and Operations Division
> European Southern Observatory
>