[alma-sw-ssr] polarization by cross-correlation

[hliszt <hliszt@nrao.edu>]

MHoldaway replies to RCrutcher:
> 
> > Moreover, single-dish data for zero and short spacings will be required.
> > Single dish polarimetry is often done by subtracting total power
> > measurements made with changes in the polarimeter (right - left, or
> > linear at different position angles). This technique severely limits
> > polarization accuracy. For ALMA, investigation of cross-correlation of
> > the 2 receivers on each single dish to derive the 4 Stokes parameters is
> > essential.
> 
> They are doing this now at the 12M.  For a few months anyway.
> 

I note that this has been done at the 140' recently -- Heiles and Turner 
used the spectral processor -- and will continue to be done at the GBT.
We have a polarization switch in the GBT's L-band receiver, but I
suppose 
we can take it out when the lack of need for it is apparent under actual 
experience.

regards, Harvey