[mmaimcal] ACA sims

[Mark Holdaway]

> 
> mark,
> 
> i haven't had time to go over the full writeup yet, but i'm curious
> how you reconcile the following two statements from your 'results':
> 
> >...
> > in the case of the DEBRIS model, the
> > improvement is substantial (more like a factor of 2
> >...
> 
> and
> 
> > However, it is very difficult to justify either the ACA
> > above the homogeneous array alone, or the ACA above the SMA.
> 
> seems like a factor of 2 improvement is pretty good justification
> for ACA above the homogeneous array (to me, at least).
> 




In the DEBRIS case, much of the scattered flux which is limiting the image
quality is due to the effects of the pointing errors on the bright compact
source.  I believe that these can be fixed pretty easily. In general, you
would need direction-dependent self-cal to solve this problem.  However,
since there is only one problem source, you can fix it to large extent
through generic self-cal (of course, you end up making a small error in
the rest of the field when you do that).

I deleted this reasoning from the writeup as I thought it was too
essoteric at this point.  So, while I haven't done the extra work, I
don't think that the DEBRIS model is a particularly telling case because
of the ease of correction.  I should go ahead with that work, though,
as one or the other array concepts may work better in the correction.

	-M