[daip] ANTEN under CALIB

[Leonia Kogan]

John,

You wrote:

>2) Under this theory of how CALIB works (and because the array during my
>observation was between A/B), I tried running calib using uvrange 0,150
>and anten 0 (that is, ALL antennas).. Much to my surprise, I got 0 good
>solutions! ("CALIB2: ERROR: NO VALID SOLUTIONS FOUND").

>HOWEVER, when I change my antenna command to 
>anten 2,4,18,22,25,24,21,17,6,7,28,19,14   (which includes basically the
>inner 4 antennas of each arm), then RERUN it -- with uvrange 0,150 --
>then it finds lots of good solutions..

The following is my try to find the explanation:

The source 3C286 can be completely resolved at the big baseline of A
configuration. Therefore the amplitudes of visibilities can jump from
big values of small baselines (<150kl) to zero of the big baselines.
At the same time the point model of the 3C286 supposes all visibilities 
to be the same for all baselines. So the measurements are too far from 
the model.
In such a situation  CALIB can (probably) have a problem find the solution.

Limiting antenna list by the inner antennas you leave only small baselines 
with approximately identical amplitudes of the visibilities.
It is close to the measurements and more simple for CALIB to find the solution.

Leonia