[daip] Confused Calibrators

[Eric Greisen]

On 02/26/2018 08:13 AM, rperley wrote:
> Eric:
> 
> How do we handle calibrators that have confused emission in the 
> distance?  3C138 (at L-band) has 8.26 Jy in the nuclear region, and 
> another 0.4 Jy is unresolved background sources -- easily visible in the 
> visibility plot.
> 
> If I run 'SETJY', it assigns the correct nuclear flux.  But in running 
> CALIB, using a model which includes all the flux, it is offsetting the 
> solutions by the total flux, rather than the nuclear flux.
> 
> How do I notify CALIB that only the components from the central few 
> cells are to be used for the scaling?
> 
> Rick

AIPS is smarter than that.  It sums the part of the model in the nucleus 
and scales the model by the flux in the SU table divided by that nuclear 
sum.  Then it uses the whole model.  Of course this function assumes 
that the whole model has the same spectral index as the nucleus but is 
better than nothing...  This is why models should be done as relatively 
nearby frequencies.

ERic