[daip] ANTEN under CALIB

[John David Monnier]

Hello,

 I have an AIPS question.  I was using calib on 3C286 to do (primary) flux
calibration.  The array was between A and B.  The "Accurate Flux Density
Bootstrapping" memo on the web indicates that for A (B) array, one should
use UVRANGE 0,150 and use 3 (all) antennas on each arm.  

So this leads me to 2 questions.

1) Why does it matter how many antennas I specify on each arm? If the
minimum # of antennas is 4 (aparm(0) 4) and uvrange is set, it would
_seem_ to have little impact, saving minimal computer time. 

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..
"CALIB2: Found           28 good solutions
CALIB2: Failed on        2 solutions
CALIB2:                  2 solutions had insufficient data"

I don't understand why it couldn't find this solutions when Anten = 0.
Does ANTEN OVER-RIDE the uvrange command? or is there some other
explanation?


I tried to find my answer looking at the EXPLAIN and HELP pages on CALIB,
but not luck.. I would appreciate any enlightenment...

Regards,
John Monnier