[evlatests] Basic Results from ACU test

[Rick Perley]

     We ran a quick ACU test yesterday afternoon, looking primarily to 
see if the oscillatory behavior seen last June was still present.

     As a reminder:  The test from last June showed superior performance 
from the new ACUs, with a single exception:
     For a short (3 arcminute on sky) azimuth move, when the source was 
transiting (i.e., the rate of change of elevation was near zero), a 
large oscillation was observed.   The period of this oscillation was 
about 10 seconds, and amplitude was a couple arcminutes.  It occurred 
only in this short throw test -- for longer offsets (30 and 6 
arcminutes), this behavior was not seen.

     Since this last test, changes in the new ACU software is believed 
to have eliminated this particular resonance.  The test run yesterday 
was to determine if this change has worked.

   As the test had to be done on a source at meridian transit, and since 
the time slot available was very narrow (a few minutes!), a rather weak 
calibrator was employed -- J2355+4950.  Hence the SNR was not high.  But 
it was high enough to state that:

     *** The oscillatory behavior seen in the June test was not present 
in the new test ***

     A better test, using a much stronger source, should be done in the 
near future to complete this round of ACU testing.