[daip] Calibration at 90cm

[Eric Greisen]

Björn Adebahr wrote:
> Hi Eric,
> 
> I am normally observing with the Westerbork Telescope and do the normal
> calibration in AIPS for L-Band and higher frequencies in AIPS. So for
> polarization calibration I can normally use the SETXY or special WSRT
> task SETVY. Now we have a dataset with full polarization information at
> 90cm. The problem here is that the calibration sources have a variable
> flux in Q and U due to the high wavelength and the Rotation Measures at
> these frequencies. Is it somehow possible to give the calibrator models
> a flux and an RM so the calibration works well for the whole observed
> bandwidth?
> 
> Thanks in advance.
> 
> Regards Björn
> 
> 
Interesting problem.

PCAL now has the ability to read a CP table as a model when solving for 
the D trerms as a function of spectral channel.  That is a binary table 
containing a big array of source flux as
      (4, Nchan, Nif)
where the 4 dimension is I, Q, U, and V and there is a value for every 
spectral channel and spectral window ("IF").  Every row of the table is 
a different source.

The issue is how to convert your source information into something PCAL 
can use.  I could give PCAL another option to read a text file giving I, 
Q, U, V as a function of frequency or perhaps a task to convert simple 
info into a CP table.  These require 31DEC11 because that is all I can 
change.  Which do you think would be useful?

Eric Greisen