[evlatests] report on modcomp-free test

[Gustaaf van Moorsel]

Report on Modcomp-free test 6/10/2007

Observation:  flux calibrator, phase calibrator, source, phase calibr-
ator.   Spectral line L-band, 2AC, 16 channels, 0.78125 MHz channel
separation, 10 seconds integrations, 30 minutes total.

During the first scan, on the flux calibrator, none of the baselines
with VLA antennas fringe.  EVLA - EVLA baselines do not fringe only
for the first 80 seconds, and produce usable data (e.g. allowing a
meaningful run of CALIB) after that.

During the second scan, on the phase calibrator, it takes all antennas
(VLA and EVLA) 60 seconds to start producing meaningful data.  During
the first 60 seconds no fringes are observed.

The third scan (source) and fourth scan (phase calibrator) do not show
any of this one-minute delay, whether on VLA or EVLA baselines.


In chronological order:


flux calibrator scan:

01:01:20	start flux calibrator scan: no meaningful values
01:03:00	start fringing on EVLA - EVLA baselines only
01:04:00	last non-flagged, non-fringing data on VLA baselines
01:04:10	last (fringed) data on EVLA - EVLA baselines

phase calibrator scan:

01:04:30	first data in scan.  No fringes on any baselines
01:05:20	last time stamp without fringes
01:05:30	fringes on all baselines
01:07:10	end of phase calibrator scan


This run was followed by an identical 30 minute run (with the only
difference that online Hanning smoothing was used).  During this run
it took 40 seconds for the scan on the flux calibrator, and 70
seconds for the scan on the phase calibrator, to start producing
reasonable data.  No different behavior between VLA based and EVLA
based baselines was observed this time.  Here, too, the third and
fourth scans behaved fine.


Gustaaf