[daip] tvstat

[Eric Greisen]

Andy Biggs writes:
 > Hi there. I've been measuring flux densities of extended sources in maps 
 > made by IMAGR using TVSTAT. It appears to be the case at the moment that 
 > TVSTAT will not report the total flux density within a shaded region if 
 > the NITER keyword in the header is equal to zero. The maps I'm working 
 > with at the moment are VLA wide-field maps, the primary beam being covered 
 > with a large number of smaller maps. Many of the maps furthest away from 
 > the pointing centre contain weak extended sources which do not get CLEANed 
 > and at the moment therefore it isn't possible to derive their flux 
 > densities easily.
 > 
 > I presume that I can change the NITER keyword and make TVSTAT do what I 
 > want it to do, but is the behaviour described in the paragraph above 
 > correct?

Yes and no.  In principle, the sum over a dirty image is zero unless a
zero spacing is given.  This is why the verb is fussy.  I have just
changed it however since in practice this is an excessive requirement.
 Of course the Clean beam parameters must have been set in any case.
If you run a MNJ on 31DEC05 this will be fixed tomorrow.  Otherwise,
use your work around.

Eric Greisen