[evlatests] ea09 below 30 degrees...

[Vivek Dhawan]

ea09 is on W02. Shadowing?

On Tue, May 26, 2020 09:18, Ken Sowinski via evlatests wrote:
| I haven't looked at pointing results recently because it hard to do from
| home.  But, on the face of it an effect that large suggests there might
| be someting loose up at the apex.  As a pointing model error is has to
| be well over an arc-min to cause consistent failures at X band.
|
| Ken
|
|
| On Mon, 25 May 2020, 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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