[obs-tap] draft summary topic 6: *Polarised data*

[Patrick Dowler]

I commented on this in the wiki page and think we *could* make pol_states part 
of the core (but allowed to be NULL). I have some suitable content in the db 
now to prototype it quickly if needed.

Pat

On 2011-03-23 15:53:04 François Bonnarel wrote:
> Le 18/03/2011 19:14, Mireille Louys a écrit :
> > Topic 6: *Polarised data*
> > This is the case when the observed flux was recorded for various
> > states of a polarizer.
> > Then the data set can be : a set of images, a set of spectra , a set
> > of spectral cubes with various polarisation flux at each data point,
> > etc..
> > It seems there is no need for a specific data product_type value here.
> > 
> > ObsTAP can be used to expose these data set by :
> > 
> > 1. use o_ucd (mandatory) with appropriate ucd value containing the
> > substring phys.polarisation like in
> > "phot.flux.density;phys.polarisation" . (cf list of observables)
> > 
> > 2. add an optional data model field: pol_states
> > It contains a  list of polarisation states.
> > Its format is an enumeration based on the FITS polarization axes
> > labels (by code, not by number, i.e. I Q U V RR LL RL LR XX Y Y XY Y X
> > POLI POLA UNDEF
> > (see http://www.ivoa.net/Documents/Notes/Polarization/ by Anita
> > Richards et al.)
> > 
> > Examples of such data sets should be worked out, and included as
> > examples in the document.
> > 
> > --ML
> 
> As allready discussed the full description of available polarization
> states requires pol_states. But for version 1.0 appropriate o_ucd is
> enough to build queries such as "Hey there, give me datasets containing
> several polarizations states".

-- 

Patrick Dowler
Tel/Tél: (250) 363-0044
Canadian Astronomy Data Centre
National Research Council Canada
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