[evlatests] EVLA L-Band Performance

[Juan Uson]

On Oct 19, 2006, at 1:34 PM, Rick Perley wrote:

>
>     One global phase jump was noted -- relative to an EVLA reference,
> all VLA antennas jumped by 30 degrees -- the same value was seen for
> both IFs and both polarizations.  The jump occurred within a scan!  It
> is impossible to say which array (VLA or EVLA) is responsible for the
> jump.
>

Dear Rick,

If you have enough signal-to-noise to solve for calib on the  
integration timescale (i.e. solint=dump_time), you can tell which  
antennas jumped because the decorrelation results in a hiccup in  
amplitude at the same time as the phase jumps.  I saw this clearly in  
the holography run of October 5 even with a dump time of 1.66 sec as  
I was observing 3C84.  In that case, it was clear that all EVLA  
antennas jumped.

I have seen no instances in the holography runs of all VLA antennas  
jumping at once; however, I have seen at least 4 cases in which all  
EVLA antennas jumped at once.

Cheers,

Juan