[daip] Re: Multi-Resolution Clean in AIPS

[Greg Ball]

Hi Eric.

>    Actually it gets it wrong all the time - no extended source is
> round - so we depend on Clean being iterative and working to undo its
> mistakes.  What we try for is to keep the early mistakes small since
> they are hard to undo in a reasonable time.

Given this way of thinking about it, I am wondering:

Do we expect all the resolutions to produce mostly positive components,
or only one?

When using the clean components as a model, e.g. in CALIB or VPLOT, how 
should we choose NCOMP?  It seems that choosing NCOMP by inspecting the 
list of components on each field might lead to an overall inconsistent set 
of components;  To ensure consistency, is it safe to use a flux cutoff in 
this case, or is taking *all* the components necessary?

> The extended source parts mostly cut down on the bed of nails errors
> and somewhat fill in the negative bowls that surround objects when
> there are too few short spacings.

Is it your experience that these corrections to the image have a big 
impact on self-calibration?

Thanks

--
Gregory H. Ball             Harvard-Smithsonian Center for Astrophysics
Graduate Student            60 Garden St MS #10, Cambridge MA 02138, USA
Astronomy Department        Email: gball at cfa.harvard.edu
Harvard University          Office: +1 617 496-4946