VLA Test/Observation Coordination Meeting
                           B.G. Clark
                         July 24, 2003


1.  eVLA

Antenna 13 is in the Assembly Building for retrofit.  Current date
for coming out is August 13.  After that time there is a lot of work
to be done installing and wiring racks and bins, and inserting modules.
About a month after that date there should be an electronically complete
antenna, ready for serious testing to begin.  One early test, though,
started yesterday - S. Durand has started a round-trip phase measurement 
on the buried fiber between the control building and the master pad, 
just jumpering a fiber pair at the pad.  As soon as the antenna is 
brought out of the building, this test will be extended to the fiber 
paths within the antenna.

As soon as the antenna comes out of the building, the VLA becomes
a 26 element array.

P. Napier urged early implementation of holography, so that if G/T
is not what is expected with the new feeds/receivers, we can find out
why before we are required to go into production.  B. Clark thinks
holography will not lag interferometry by much.

P. Napier raised the question about where the first few eVLA antennas
should be placed.  For operational reasons, it is desirable to 
put all antennas on the same arm, so that we can stop maintenance
on one waveguide as soon as possible.  However, this will result in
a linear array for observations outside the current VLA bands, and
for early observations with the WIDAR correlator, with resulting
disadvantages.

3.  Lightening

K. Sowinski reports that lightening struck the control building early
in the evening on July 11.  Various problems were generated by this, but
the array was soon brought back to ostensibly be on the air.  However,
data was in fact not valid.  Saturday morning, this was traced to a 
problem with the drivers of the wires leading from the correlator room
to the Modcomps.  The spare I/O board for the array processor was 
swapped in, and the system once again was ostensibly working.  After a
while, it was discovered that various line modes (1B, 1D, 4, PA) were
not working.  The problem remained unresolved until July 22, when it
was discovered that it could be traced to a rev level difference between
the two boards.  On the same day, the original board was repaired, and
will soon be tested in the system.

3.  Antenna 1

K. Sowinski reported last month that since early May, antenna 1 has very 
large pointing errors, especially at low elevations, approaching an arcminute.  
The servo group investigated and found problems with the azimuth encoder
coupling, and antenna 1 seems to be pointing OK now.

4.  4

R. Perley notes that the 4 meter dipoles are mostly up, with the last four
being installed today.  He will shortly do the usual checkout to find 
broken wires, reversed polarizations, etc.

5. Polarization

R. Perley and T. Cornwell are working on beam polarization effects, using 
test data collected at 20 cm wavelength.  TC is developing software to
properly deconvolve/correct for the effect.  RP claims that there are clear 
time variations, of order 1%, seen in the data, most likely to be interpreted 
as a change in D terms with time.  The timescale of these effects is not yet
clear.