[daip] FIXBX bug?

[Andy Biggs]

Hi Amy. Sorry to bother you again, but I may have found a bug in FIXBX. 
Firstly, I should say that this is a wonderful task that's made my life 
a lot easier. However, after changing my faceting scheme (moving to a 
larger cellsize and therefore covering a larger area of the sky) and 
using FIXBX to re-set my clean boxes, I've found that certain fields in 
my map are not being cleaned by IMAGR, despite them containing sources.

On closer examination it turns out that the output boxfile from FIXBX 
contained clean boxes for these fields which didn't correspond to any 
sources in the field. I've done some tests that show that the problem is 
probably occurring when FIXBX comes across a situation where, after 
mapping the clean boxes to the new faceting scheme, a field does not 
contain any 'new' clean boxes. If that field number has 'old' clean 
boxes from the previous faceting scheme then it leaves them in place. 
These naturally don't correspond to any emission in the new field 
resulting in IMAGR never trying to clean that field even if it contains 
bright sources. FIXBX should, of course, either write out no boxes for 
that field or write out one as large as the field itself. At least, I 
think this is what is going on. Otherwise, FIXBX is working perfectly.

In some ways, this problem mimics that in CCEDT where the old clean 
components are left in place if the output file would contain none.

Cheers,

Andy

-- 

Andy Biggs
ESO, ALMA Regional Centre
Karl-Schwarzschild-Strasse 2
D-85748 Garching, Germany

tel. +49-89-32006471
fax. +49-89-32006898