[evlatests] ea09 below 30 degrees...

[Mark Claussen]

Good thing Vivek thought about this.  I wouldn't have.... but
in hindsight, shadowing certainly fits your description of the
issue.

Mark

On 5/26/20 10:12 AM, rperley via evlatests wrote:
> And indeed, this is exactly what was wrong.  Only this antenna was 
> shadowed -- by ea12, sitting on N01.
>
> Sorry for the red herring.  Shadowing in C configuration is rarely an 
> issue...
>
> Rick
>
> On 2020-05-26 11:54, Vivek Dhawan wrote:
>> 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
>> |>
>> |> _______________________________________________
>> |> evlatests mailing list
>> |> evlatests at listmgr.nrao.edu
>> |> https://listmgr.nrao.edu/mailman/listinfo/evlatests
>> |>
>> |
>> | _______________________________________________
>> | evlatests mailing list
>> | evlatests at listmgr.nrao.edu
>> | https://listmgr.nrao.edu/mailman/listinfo/evlatests
>> |
>
> _______________________________________________
> evlatests mailing list
> evlatests at listmgr.nrao.edu
> https://listmgr.nrao.edu/mailman/listinfo/evlatests

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://listmgr.nrao.edu/pipermail/evlatests/attachments/20200526/e13022c0/attachment.html>