[evlatests] ea09 below 30 degrees...

[rperley]

We ran the 'gain-elevation' script last night.  The purpose is to 
remeasure the gains as a function of elevation, from X through Q bands.  
The method uses 'double-referenced pointing' -- referenced pointing is 
done first at X-band, and these results are used to 'peak up' Ku-band, 
then K-band, then Ka, and ending with Q-band.  This is to ensure the 
antennas as peaked up on the source for each band and elevation.

Observations started with the source (J2007+4029) at 11 degrees 
elevation, and proceeded cyclically  through the bands until meridian 
transit.  For each cycle, the old referenced pointing solutions were 
'forgotten' when X-band was next scheduled.  This procedure worked very 
well for nearly all antennas.  But not ea09...

Something is seriously amiss with this antenna, for elevations below 30 
degrees.

All referenced pointing attempts failed, including the initial X-band 
one, until the antennas reached 23 degrees elevation.  At this 
elevation, the solution offset parameters looked good, but in fact were 
not, as the gains (at X-band!) were low by 40%.  As the antenna rose, 
the gains rapidly increased until, at elevation 34 degrees, all looked 
normal at all bands.  From then until meridian transit, all was well.

I have no idea what is wrong here.  Any ideas?

Rick