VLA Test/Observation Coordination Meeting
                           B.G. Clark
                        December 16, 2004


1.  EVLA tests

K. Sowinski and R. Perley report first fringes with Antenna 14, at X
band, on December 2.  It currently has only a single IF and a a single
receiver connected.  Sensitivity is low because no pointing has been
done on it.  R.P. further reports that for antennas 13 and 14 at X
band, the scatter in amplitude and phase is similar to that seen on
the rest of the array.  However, on the Antenna 13 - Antenna 14 baseline,
there is a strong sinusoidal modulation in amplitude, of about 2 Jy
peak-to-peak.  Observations were being made in spectral line mode, and 
the modulation is broadband, thus representing a huge closure error.

Further observations were made on December 14.  At that time, the
two EVLA antennas had a very large phase wind, with a two or three minute 
period (one minute on the baseline between them).  [later determined to 
be due to the time synchronization being disconnected -bgc].  At this 
time the period of the sinusoidal amplitude variation was about thirty 
seconds.  The cause of this phenomenon remains unknown.  

2.  Calibration models

A. Mioduszewski is constructing models of the flux calibrators (eg 3C 48,
3C 286), to be used in calibrating ones data with insufficient time on source 
to model the source on ones own.  Models have existed for some time at the 
shorter wavelengths; A.M. is extending them to 6cm and 20cm.  They will
eventually ship with AIPS.

3.  Water vapor radiometers

C. Chandler reported on lab tests of a new version of the WVR using MMIC
technology.  In previous lab tests on the old design, an Allan Variance
on the system temperature of about 10^-4 was achieved on each of the
three channels, and a relative stability approaching 10^-5 on adjacent
pairs.  The new design (courtesy M. Morgan) has five channels, with 
off-line channels added at the ends of the band.  It is now being tested 
in the lab.  The needed 10^-5 stability between adjacent channels has
not yet been obtained.  In fact, a hysteresis effect is being observed,
in which the level is systematically lower when it is rising than when
it is falling (the level variations are probably due to residual thermal
effects).

4.  4 meter band

R. Perley reports that the dipoles are up and working, and observations 
are starting.