[evlatests] Peculiarities from last night's test

[Rick Perley]

    More tests were run in preparation of the flux density run this 
weekend.  Below are some notable oddities. 

    A) Curious flagging issues:

    Antennas 5, 13, and 21 were out of the array for what the log stated:

    5:  subreflector stuck
    13:  locked out
    21:  subreflector e-stopped. 

    These three 'dead' antennas were handled differently by the system 
flaggers:

    Antenna 5:  Was flagged, correctly, as bad for all IFs, all bands.  

    Antenna 13:  Was flagged, correctly, as bad for IF #1 only.  It was 
not flagged in IF#2 -- but there were no fringes at any band. 

    Antenna 21:  Was not flagged at any band, at either IF.  The data 
showed good fringes at P-band, but no fringes at any other band. 

    B)  Curious X-band incoherence between arrays. 

    I observed three sources at all bands.  At X-band *only*, the two 
arrays were completely incoherent *for the last ten seconds only*, for 
all three observations.  More specifically:
       - The VLA x VLA baselines continued on with no change in 
amplitude or phase. 
       - The VLA x EVLA baselines became pure noise. 
       - The EVLA x EVLA baselines continued on with no change in 
amplitude, but a discontinuous change in phase.  There was a single 
(0.416 second) record where the amplitudes dropped, corresponding to the 
moment when the phase jumped.