[daip] bandwidth smearing

[Eric Greisen]

Andy Biggs writes:
 > Hi Eric. This is probably a long shot, but I was wondering if there was a 
 > way in AIPS to deconvolve a source whilst taking into account bandwidth 
 > smearing. I'm mapping combined MERLIN/VLA wide-field data in order to 
 > measure source sizes and need to take bandwidth smearing into account.
 > 
 > If we were deconvolving in the image plane I presume that one could 
 > convolve the dirty beam with a Gaussian that represented the smearing and 
 > use that to map the structure as usual. Things would appear to be much 
 > more difficult in the u,v plane. One obvious problem is that the MERLIN 
 > and VLA data have different channel widths and AIPS has no way of knowing 
 > this from a combined dataset.
 > 

In the image plane, SAD, IMFIT, JMFIT all have options about bandwidth
smearing.  There is no way I know of to do anything in the UV plane.
One Cleans with point models so there is no way to do somethi ng about
smearing there.  The channel width issue may be more important.  If
you are doing bandwidth synthesys, then the different channel
separations should be be handled differently but aips can't now do
that.  It has been a long-time wishlist to allow multiple input data
sets but that is very hard to do.

Regards,

Eric Greisen