[daip] AIPS: SAD for mosaicked data

[Matthew Sharp]

Dear Designated AIPs,

  I've been working on sets of mosaic maps made with 8GHz VLA data
(thanks again for all of your help getting this far!).  I seem to be
able to generate calibrated SNR maps of my mosaicked fields which take
into account the mosaicked beams accurately.

   I want to find a catalog of sources in this map.  My mosaic has
non-uniform sensitivity, and so I need to look for peaks in this SNR
map, and not in the actual, Jy/beam
 signal map.

   using SAD, I can get a list of all sources that show up at 5sigma
in my mosaic, but the flux that is reported is in units of the ratio
of signal over noise that I used to compose the map.  I'm wondering
about how best to find the real, beam corrected fluxes of these
sources in Jy/beam.

   My thought is to use SAD to generate a residual SNR map, and then
to subtract the residuals from the map itself, leaving zeros except
for my 5 sigma sources.  I can then multiply this difference map by
the noise map, yielding a map with only my bright sources, but in Jy.

   As for the primary beam correction, I understand that FLATN can do
this for me when i generate the maps, but I'm not certain if it's
necessary to set PBPARM(1)>0, or if this correction happens no matter
what.

  Now I should have a map, in Jy, of my mosaic field, with zeros
except for 5 sigma sources, which should remain as gaussians.  I can
then use SAD a second time to extract fluxes and other parameters from
this map.

   I'm wondering if this method is likely to produce what I want, or
if there is perhaps a more straightforward way of extracting source
fluxes from this kind of signal to noise map.

thanks!

Matthew