[evlatests] ea09 below 30 degrees...

[Dave Parker]

Is it possible we have quad leg sag?

Dave

On 5/25/2020 3:53 PM, rperley via evlatests wrote:
> 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
>
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