[evlatests] TBRISK Dec 15 UT 2225 to 2303

[Chris Carilli]

but not at source changes?
that would be consistent with what i saw last week.
band changes lead to phase jumps, but the EVLA
antennas do not jump together, ie. the phase jump is
different for ant 14 and 16.
cc

Walter Brisken wrote:

>
> Yesterday I ran a simple continuum test file that switched between two 
> sources and three bands in the following order to see when phases did 
> not return to their correct value.  Except for the 5 minute first scan 
> all scans were just under 2 minutes long.  Integration times were 3 
> seconds.
>
> First the peculiarities of the data:
> 1.    L-band IF B was dead on antenna 16.  All other bands/IFs worked.
> 2.    Antenna 14 IF C had poor amplitude stability at C and X band
> 3.    (Really weird!) VLA baseline 4-28, all IFs at X-band only were 
> very noisy (but shows some sign of coherence), but 4-16 and 14-28 
> looked fine.
> 4.    Antenna 14, IFs B and D showed (both LL pols) showed no fringes 
> for first scan, very weak fringes on second scan, and normal strength 
> on subsequent scans.  IFs A and C were OK.
>
> Table of scans
>
> 0137+331  CC
> 0136+478  CC
> 0137+331  CC 0136+478  CC 0137+331  CC 0137+331  LL
> 0137+331  XX
> 0137+331  CC 0136+478  CC 0137+331  LL
> 0136+478  LL
> 0137+331  LL
> 0137+331  XX
> 0136+478  XX
> 0137+331  CC
> 0137+331  XX
>
> At every band change phases on EVLA IFs got phase jumps.
>
> Plots are available in /home/parallax/evla/tests/20051215 -- the 6 
> postscript files are VPLOT outputs.  Red is for IF A / C for RR / LL 
> respectively and Blue is for IF B / D for RR / LL.  No calibration has 
> been done.
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