[evlatests] Quick Test Results -- not good

[Rob Long]

Are we sure that the time issues (MIB/device time) are not haunting us 
again?

Rob

Rick Perley wrote:
>    Following an X-band pointing correction made by Vivek and Barry this
> afternoon, I ran a quick check of all EVLA antennas at L, C, X, and K 
> bands.
> 
>    For each, I did a pointing scan on 3C84, followed by a short on-source
> integration to check sensitivity, etc.
>    Results are not encouraging:
> 
>    1) Pointing.  No pointing solutions were obtained at any band for 
> antennas
> 14 and 16.  Antenna 13 gave only one solution (a very odd one ...) at 
> L-band,
> and none at any other band.    Antenna 18, which purports to work at 
> X-band,
> gave no solutions.
>    2)  Amplitudes.  Although stable fringes were seen on all IFs for 
> antennas
> 13, 14, and 16, all amplitudes are very low.  For antenna 13, they are a 
> factor
> of 3 to 10 too low.  For antenna 14, the factor is 20 at L-band (all 
> IFs) and
> 3 to 5 at all other bands.  For antenna 16, it's a factor 15 to 20 for 
> all bands,
> all IFs. Antenna 18 gave no data at all at X-band.       However -- the 
> situation is not as simple as above.  The EVLA-EVLA
> baselines do not follow the rules above -- they have amplitudes usually 
> much
> higher than the geometric mean of the attenuation factors listed.  
> Hence, they
> have what we call in the business 'large closure errors'.
>    The low amplitudes might be suspected to be the cause of the failed
> solutions -- but this is not sufficient.  I used 3C84, about 15 Jy at 
> C-band.
> Even with the attenuation of a factor of 3, the amplitude should easily
> pass the check in PEEK.
>    The EVLA antennas worked well at C-band earlier in the afternoon, during
> the pointing run.  Something bad seems to have happened since then.
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