[evlatests] Pointing Gone Wild -- May 2020 Edition

[rperley]

All:

This phenomenon is far more common than may be appreciated.  Usually, 
the 'wandering' is small, and hardly noticed.  But on occasion, (as 
shown especially in ea25) it can be large -- up to an arcminute over a 
time span of an hour.

I will review the data I have from these four recent observations (two 
in January 2019, two in May 2020), and circulate later today a summary, 
in the hope that this will help narrow the range of possible causes.

Rick

On 2020-07-02 10:22, Dave Parker via evlatests wrote:
> That is a good idea 25 and 18 are both old ACU's
> 
> Dave
> 
> On 7/2/2020 8:07 AM, Leon Abeyta via evlatests wrote:
>> Is this also something that can be sorted between new ACUs and old 
>> ACUs, or is that not a factor here?
>> 
>> Leon
>> 
>> On 7/2/2020 7:25 AM, Dave Parker via evlatests wrote:
>>> When you can get the info from your office I would be interested in 
>>> how many of those antennas have had bearing changes and then seed if 
>>> we have anything to compare before and after bearing change. I 
>>> realize we may not be able to find a lot of before data on many 
>>> antennas.
>>> 
>>> Dave
>>> 
>>> On 7/1/2020 2:22 PM, Ken Sowinski via evlatests wrote:
>>>> On Wed, 1 Jul 2020, rperley via evlatests wrote:
>>>>> 
>>>>> The amplitude of this effect (notably ea25 in the 2020 data, and on 
>>>>> ea18 in the 2019 data) suggests that this is a software-driven 
>>>>> offset -- the antennas, for whatever reason, were told to move off 
>>>>> source. But perhaps somebody can provide an alternate explanation.
>>>> 
>>>> Sure.  Atl east for ea25.  Ever since this antenna had a bearing
>>>> replacement years ago we have been struggling to explain anomalous
>>>> poiting associated with a particular azimuth.  There is a small Az
>>>> range where the pointing changes by about an arc-min, as you say,
>>>> mostly in elevation.  ea25 is the best example, but there are other
>>>> antennas with similar behavior.  Notes aobut others are in my
>>>> inaccessible office.
>>>> 
>>>> Ken
>>>> 
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