[evlatests] Tsys Jump!

[Rick Perley]

    A curious effect occurred at the end of the last pointing test.  The 
top-level cause is obvious, (as noted below) -- but why things came out 
the way they did is a mystery to me ...

    The last scan had a stoptime of 09:02, IAT.   At this time, there 
was a dramatic change in amplitudes on all antennas.   Yet there was no 
change in phase, or in general behavior.  Looking more closely, we find 
that at 09:02, all recorded Tsys values jumped by large values -- 
typically tens of degrees, up, or down.  (Some change by over 100 
degrees!)    The change in visibility amplitude is due to the change in 
recorded Tsys. 

    So, it would seem that the system found new values for Tsys, but 
continued to observed at K-band, nonetheless. 

    One smaller point -- antenna 18, at K-band at least,  is recording 
some Tsys values in (believe it or not!) TeraKelvin!