[evlatests] C-band polarimetry -- good news

[Rick Perley]

I've carefully reduced the C-band polarimetry data taken last Friday. 

The (pleasing) bottom line is that all the antennas (both EVLA and VLA) 
show superb stability in the cross-polarization.  There is a small 
global phase variation in the observed position angle of 3C286 of about 
3 degrees, which is conceivably due to ionospheric Faraday rotation ( 
this corresponds to about 15 rad/m^2 -- a bit larger than normal, but 
probably within range for these daytime observations).