[evlatests] Jun28 data

[Vivek Dhawan]

I loaded data starting at UT 01:00 onwards, selected by
timerange since the baptizer always outfoxes me.

I got a 3min bit of 3C273 at start, 10sec integrations,
from SYSSTART, then a gap of ~12min before my file, which
was all flagged. (Walter had declared flags were working
around 0h UT.)

My file also had 3C273 by 3 names, offset 0, +0.9,
-0.9 sec in RA, 10min scans, 1.6s integration continuum.

some quick notes:

1. All the 1.6s data amplitudes are lower than the 10s data
    by a factor 2-3. Did FILLM or IDCAF forget a scale factor
    in putting both data into 1 file?

2. The source offset of +0.9s is about right in stopping
    the fringe winding on VLA antennas (EVLA then winds.)

3. The flags at the source changes are just 1 visrec long
    (only 10" antenna motion) but appear to work fine.

The next 2 items are probably minor - my guess that it is just
individual antennas misbehaving, but maybe its more serious.

4. There are (Rick's terminology) short shallow drops in
    amplitude, a single point at a time is low by a few to
    10%. These appear rare and quasi-random, except on ea26.
    There is no phase signature (that i could see)

5. There are amplitude modulations of about 5% on EA 13
    and 14, on 30sec timescale, which don't look like source
    structure. There is a phase modulation by a few degrees.
    (Could this be EDFA related?)

V.