[evlatests] Baseline fitting and phase jumps

[Vivek Dhawan]

Recent baseline runs: (all at 50MHz continuum, standard Fluke settings)

date         band                                 result / comment

Sep 12       X      EA13, 16 can be fit - rms ~40deg each, but a fit 
nevertheless.
                            EA14 cannot be fit. ea24 not used.  ea18 is 
good, as usual.
                            No phase jumps seen.   Last baseline run 
before move.

Sep 25       X     After move (13 14 and 16 moved, I believe. 18 did not)
                            3 phase jumps on ea18, otherwise well 
behaved.  EA13, 14, 16, 24
                            all have wild phases, cannot be tamed by 
position adjustment.

Sep 26       C     EVLA (i.e. 13,14,16, 18) have 5 phase jumps (and 4 
reverse jumps)
                            by ~90 deg. relative to the VLA - all 
antennas jump together, all IFs as
                            well. EA13 has 1 extra jump, all IFs. 
Otherwise, the phases are great -
                           13, 14, 16 and 18 all produce a good baseline 
fit, with residuals of 10-15
                            deg,  (using EA18 as reference).
                            Since this is the only full baseline at C 
band, I don't quite believe it yet.

Sep30        X     Back to business as usual - EA18 well behaved, except 
for 1 jump of +90
                            followed an hour later by a return. EA13, 
14, 16, 24, 26 all too wild to
                            tell if they have phase jumps or not.