[daip] SetFC - bparms request

[Lorant Sjouwerman]

Eric,

When you have time, I have a simple request (I think)

in setfc:

   BPARM.......(1) The radius in degrees to be covered fully by
                   overlapping fields.  <= 0 means do not do fly's eye
                   list of fields.  < 0 => do not include catalog sources
                   within abs (BPARM(1)) of the origin.
               (4) Radius for the search in the catalog for interfering
                   sources.   < BPARM(1) => no search.  Try 30 for 74
                   Mhz imaging.  All sources outside the center of the
                   outermost fly's eye field (n.b. < BPARM(1)) and
                   < BPARM(4) are included if they meet the flux
                   criteria.

I want to extend this to have an inner radius to avoid NVSS sources. For the 
pipeline I image the full primary beam, eg bparm(1)=0.25 for 1.4GHz. I think 
it is a good idea to include facets for NVSS sources, so bp1>0 and bp4=1. 
This will also do better imaging for sources close to the outer parts of the 
primary beam in case they fall within bp1. However, if the target source is
an NVSS source (or the NVSS source is very close to the phase center), using 
setfc like this will end you up with two facets on the center, slowing down
the imaging without providing new insight. I see no way to have an inner NVSS 
radius other than bp1, which I think is too large if you do the full prim.bm

So in addition to an outer image radius = inner NVSS radius, and an outer
NVSS radius I request an inner NVSS radius which can be between bp1 and bp4

I realize that BPARM is full (10 items), so maybe FACTOR (fraction of bp1)
can be used - I presume I'd set it to 0.6*bparm(1) typically to make facets 
for NVSS sources eg > 0.15 deg (at 1.4GHz) but not in the dead center





Regards,

Loránt Sjouwerman - Scientific Services - lsjouwerman at nrao.edu
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