[evlatests] Results from WIDAR0 first data ...

[Rick Perley]

    Lots of interesting results to report from the run taken yesterday.

    1) The 80 minutes of data, 1 second averaging, 4 subbands, single 
polarization, 1024 channels per spectrum, generated 10.5 GB data in the 
UVFITs format.  I'm going to need a seriously larger, faster machine to 
process future databases ...

    2) Antenna 23 had the effect already noted. 

    3) Large delays are seen.   Using FRING, these were solved for with 
1 minute resolution, using antenna 2 as reference.  All subbands have 
nearly the same value for each antenna.  The long-term stability (over 
80 minutes) is excellent -- changes in delay over that period are much, 
much less than 0.1nsec.  There is a ramp-like delay residual, of about 5 
minute period, at the 0.1 nsec level -- this is seen on all antennas, so 
must originate with the reference antenna (at the center of the 
array).    The delay values are:

    1   56.8 nsec
    2   0   (ref)
    3   8.8
    9   -2.0
    18   12.4
    19   9.0
    24   -2.0
    25   9.6
    28   10.0

    4)  Antennas 1, 3, 9 and 25 have regularly spaced phase jumps of 
*exactly* 180 degrees.  (Alternatively, it could be antennas 2, 18, 19, 
24 and 28 which are jumping -- the point is that there is a subset which 
jumps, and a subset which does not).  All subbands jump identically.  
The times of the jumps are:
    20 45 27  (hours, minutes, seconds, IAT)
    20 56 27
    21 07 48
    21 19 08
    21 30 28
    21 41 28
    21 53 08

       that is -- every 11 minutes and a few seconds, but always on an 
'x8' in the seconds column. 

    5) Antenna 24 has a regular sinusoidal (or triangular) amplitude 
modulation, of 2%, with a period of 5.5 minutes.  The sensitivity of 
this antenna (as judged by the amplitudes, which I gather are essential 
corrrelation coefficients) is also low, by a factor of 2 to 3, below the 
others.  There is no phase effect. 

    6) Antennas 1, 19, and 25 have low level unsteadiness in their 
amplitudes -- much less than 1%.  The remaining antennas are 
astoundingly stable! 

    7) Antenna 1 also has weird, large phase wanderings, which are 
common to all subbands, and are most unlikely to be atmospheric in 
origin, as all the other antennas have much smaller variations which 
look just like atmospheric fluctuations. 

    That's all for the initial summary.