[evlatests] K-Band 'Failure to Tune' Statistics

[Rick Perley]

    I have (very laboriously) gone through the K-band 'flux densities' 
run, looking for scans where antennas failed to provide fringes when I 
had expected them to do so. 

    There are a total of 203 K-band observations, centered at 22.805 and 
18.550 GHz, if IFs AC and BD respectively.  The previous observation was 
always at Ka-band, at 36.500 and 28.770 GHz, in IFs AC and BD, 
respectively. 

    Some 'quasi-global' peculiarities are noted:

    a) ea 13 never provided fringes in IF 'A', but was fine in IF 'C'.  
(As expected, this difference was not seen by the system flager).
    b) ea05 never provided fringes in IF 'B', but always did in IF 'D'.  
Same flagging comment. 
    c) ea19 went 'offline' about halfway through the run, and never 
returned.  This was flagged properly. 
    d) ea4 'vanished' for about 8 hours, then returned, but in a rather 
unsteady state.  The system flagged the 8 hours when no fringes at all 
were seen. 

    Beyond these 'global' situations, there were at least 53 instances 
where an antenna (either in AC or BD or both) failed to fringe when the 
adjacent scans at the same frequency were fine.  In no more than 6 of 
these did the system flagger flag the data.  This works out to about a 
1% failure rate:  (53/(203*27) ~ .01) 

    General impatience deters me from providing a detailed list of the 
individual failures.  But if any of you wish to see this, I will do so.