[evlatests] Ad Hoc Meeting today on S-band Switched Power

[Rick Perley]

     All:

     I've reserved rm 317 today at 2:30 for a <30 minute discussion of 
S-band switched power.  Something is seriously wrong, and we need a 
meeting of minds to talk about what to do about it.

     Background:

     The recent 10.5 hour S-band beam holography provided excellent 
visibility data, apart for a single problem affecting the LCP, and which 
is undoubtedly due to the passage of Sirius satellite S3, near transit.  
This interesting (and not unusual) event requires correction of the data 
from our switched power monitor.
     However, it was quickly found that, although the event we were 
hoping to correct was in the switched power (good!), the values of PDif, 
for nearly all SPWs are varying by large degrees (factor of a few), 
completely independently for different SPWs and polarization, and are 
completely uncorrelated with the observed visibility gains (very very bad).

     I'll show a few plots to illustrate these points.  Then I'd like to 
hear suggestions of what we can do to understand what is going on.