[evlatests] Today's tests

[Rick Perley]

    We ran the 400 ms continuum checks at C-band and X-band. 

    C-Band.

    No fringes were obtained from either 14 or 16. 

    X-Band. 

    Good fringes were obtained. 

    a) The multi-state levels noted on Friday are gone.  All IFs give
strong, stable results. 

    b) 16C has a peculiar sudden 50% drop in amplitude, followed by a slow
(15 second) recovery -- similar behavior to that on Friday. 

    c) Baseline 14 x 16 has a 6% amplitude closure error.  There is no
phase closure error.  The amplitude error is the same on all 4 IFs. 
(This is the same closure error we had last Friday at this frequency). 

    d) The premature amplitude drops seen at the ends of the scans are
gone. 

    e) Phase connectivity between scans is excellent.
            
                         BUT

    f) Antenna 14 (BUT NOT 16) has a clear phase dependence on elevation 
or declination.
If we assign zero phase to obsevations at 40 degrees dec (near transit), 
then observation
of a source at 51 deg has phase -10 deg, a source at 70 dec has phase 
-35, and a source
at dec 78 has phase -55.  (The error increases rapidly with increasing 
declination or decreasing
elevation).   This cannot be atmospheric model effect, since this phase 
behavior is completely
absent on antenna 16. 

    g) Sensitivity looks close to normal on RCP -- not more than 10% 
high.  LCP is a little
worse, but perhaps there are some oddities in the data.

    h) Tsys looks good. 

    Of all these things, the one that worries me is the closure error.