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

[François Bonnarel]

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".