[evlatests] Phase stability of ea27 {External}

[Drew Medlin]

I think there is an intermittent hardware failure on ea27 that causes the phase jumps Rick saw because we saw this sometimes in VLASS during BnA. We would typically see it affect some scans, but not all. Here’s a sample plot form the pipeline showing phase solutions vs. time (each point is essentially one calibrator scan except at the start of the observation). This shows ea27 phases start to change dramatically about half-way through this VLASS observation from the 13th. 



Cheers,
Drew



Drew Medlin		
dmedlin at nrao.edu

VLA Scientific User Support
National Radio Astronomy Observatory

> On Jun 30, 2023, at 11:04 AM, Bryan Butler via evlatests <evlatests at listmgr.nrao.edu> wrote:
> 
> 
> It's a good point, but that wouldn't cause the behavior that Rick sees. It would cause a diurnal sinusoidal error which got worse with higher frequency, not random amounts for all bands, and changing between scans.  Seems like a loose connection maybe?  But would have to be after the converters.
> 
> 	-Bryan
> 
> 
> Catarina Ubach via evlatests wrote on 6/30/23 10:48:
>> Antenna 27 baselines parameters have not been updated.
>> Catarina
>> -----Original Message-----
>> From: evlatests <evlatests-bounces at listmgr.nrao.edu> On Behalf Of Rick Perley via evlatests
>> Sent: Friday, June 30, 2023 10:09 AM
>> To: evlatests at aoc.nrao.edu
>> Subject: [evlatests] Phase stability of ea27
>>  From data taken last night, it is noted that ea27's phase changes by large, and seemingly random amounts at all bands observed (L, S, C, X, and Ku).  This occurs between scans, and is not seen on other antennas.
>> Rick
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