[evlatests] X-band Results

[Rick Perley]

    At X-band, from yesterday's tests:

    1) Antenna 25 was alive and well, but antenna 3 gave no fringes.  
(This is the reverse of the situation at C-band, where 25 was all noise, 
but antenna 3 was fine).  The C-band observations immediately preceded 
these X-band observations.

    2) For reasons unclear to me, the amplitude stability for all 
antennas was very 'ratty', with short-term fluctuations (of a few 
percent) not seen in any preceding observations. 

    3) Delays are the same (within 1 nsec or so) as the C-band values.  
Antenna 25's delay (not measured at C-band) was 17.8 nsec. 

    4) Three 180 phase flips were found:  22:49:58, 23:00:57, and 
23:12:58.  Note the time intervals of 11:00 and 12:00 between them.  (At 
C-band, the interval between the observed pair of flips was 11:20). 

    5) No sign of any phase oscillations was seen!   All phases track 
well, with no oscillations above the expected noise.  (Note, however, 
that it's a bit harder to judge this on 3C273, which is an 18-arcsecond 
double source, so both the amplitudes and phases are sinusoidally 
varying, albeit with a very long period ...).  [Hint:  it's better to 
observe a pure point source ...]

    In both the C band and X band data, a few zero-coherence (amplitudes 
= 0.000) records are found.