[evlatests] Referenced Pointing Statistics

[Rick Perley]

     The semi-regular 'flux densities' program was executed late last 
week.  Although determining the flux densities and polarizations of the 
standard calibrators is a major goal, the program is better viewed as a 
true, and severe, 'stress test' of our array capabilities.

     In short, there were 200 observations of 24 sources.  Each 
observation consisted of a short (typically 30 seconds) observation at 
each of the nine observing bands -- hence about 1800 individual 
observations.  (That's a lot of band changes!).

     The 24 sources comprise the standard 'stable' calibrators, plus a 
selection of proposed compact, stable objects, mostly in the south, and 
a half dozen proposed calibrators near the galactic center.

     This report is on the results of the referenced pointing. There are 
likely to be numerous subsequent reports on other characteristics and 
problems discovered as the processing of the data proceeds. :-)

     As noted, there were 200 separate executions of referenced 
pointing.  With 27 antennas in the array, that gives 5400 solutions.  
(Actually, closer to 5250, as ea21 was stowed part way through the run, 
due to motor issues).

     Of the 5250 potential solutions, only 15 failed.  That's an amazing 
99.7% success rate!

     But it's actually even better than this -- of the 15 failures, 13 
were due to antenna shadowing.  So that leaves only 2 failures of 
undetermined origin -- a 99.96% success rate.  I'm impressed.