UCD problem in SSA/SpectrumDM

[Alberto Micol]

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