[evlatests] R-L delays -- HUGE!

[Rick Perley]

    I'm going through the full polarization data of 3C286, taken at 
L-band on 3C286 (a strongly polarized source). 

    There are some remarkable delay issues:

    1) Delays within the RR side are generally where we have seen them 
-- typically 20 nsec.  Two antennas are especially large -- 2 (-77 nsec) 
and 9 (-88 nsec), w.r.t antenna 1. 
    2) Delays within the LL side are much larger, with seven antennas 
having delays more than 50 nsec, and one being more than 200 nsec!! 
    These are easy to calibrate out, and I did so. 

    But the biggest surprise comes from the delays in the R-L 
correlators -- the time delay between the two polarizations.  After 
removing the 'parallel-hand' delays, I find the RL and LR correlators to 
have a 305 nsec delay error -- of opposite sign in RL to LR (as it 
should be), and the same for all baselines (as it should be). 

    Question to AIPS-experts:  I don't know how to get AIPS to correct 
for the delay between R and L.  The phase correction ('POLR' in the 
program CLCOR) is not the correct operation.  Can AIPS do this? 

    Other than this -- the X-hand amplitudes look good, and are at about 
the right level.