[evlatests] ea15 tardiness ...

[Rick Perley]

     Antenna surface holography was done Saturday night, at Ka band, in 
ideal conditions.  The data quality appears to be superb.  All 28 
antennas fringed beautifully.

     One antenna  -- ea15 -- behaved abnormally, but only under a 
specific situation.

     The script had eight referenced pointing observations,  done at 
X-band.  For five of these eight, ea15 was slow to return to  source 
following the last X-band off-source pointing observation.   I know it's 
an issue of antenna motion, rather than tuning, as the data were 
properly flagged.
     Examination of the flag table shows that the problem is in the 
subreflector rotation -- the 'antenna off source' and 'focus error' 
flags show these motions were successfully completed in the usual time 
frame.  However, the 'subreflector position error' shows that this 
motion was not completed during the 40 second duration of the calibrator 
observation.
     For all other antennas, the subreflector rotation was completed 
within 15 seconds for every one of the eight referenced pointing 
observations.  And for three of these eight referenced pointing 
observations, ea15 did get its subreflector back into position within 
the same time as all other antennas.  For two of the five tardy motions, 
ea15's subreflector reached the correct position at the end of the 40 
second scan (so there was exactly one good integration).

     Rick