[evlatests] EVLA Polarization

[Rick Perley]

    Observations of another strong calibrator were made last night, at 
L, C, X and K bands, to see if the polarization troubles noted yesterday 
repeated at L-band, and were seen at any other band.  Observations were 
two minutes long at each band, and cycled round and round the bands in 
the order given above for four hours.

    Bottom line: 

    In *this* database, all polarization characteristics were steady at 
*all* bands.  None of the problems seen in the L-band observations from 
the weekend were seen in last night's data.  EVLA antenna polarizations 
at L-band are higher than VLA antennas (referenced to a VLA antenna), 
but not hugely so.  And they seem to be stable. 

    I used an identical calibration routine in these new data, which (at 
L-band) were taken at identical frequencies and bandwidths to the 
weekend's observations. 

    I'm open to suggestions.  I have no useful explanations of my own. 

    There were many other issues identified, which may be reported on a 
different day.