[daip] AIPS Polarization Calibration

[Eric Greisen]

Julie Grant wrote:
> Hi,
> 
> I am running AIPS pcal in the 31DEC2010 version of AIPS.  I have 7 
> channels with which to calibrate in polarization.  I followed the 
> instructions in the AIPS cookbook and using the help file.
> 
> For my 7 channel cube at 1.4 GHz I have run PCAL using:
> 
> calsour '1331+305','1634+627'
> solint 2
> soltype 'appr'
> docalib 1
> gainuse 2
> flagver 1
> refant 6
> doband 1
> bpver 1
> pmodel 0
> prtlev 1
> ichansel 1 7 1
> spectral 1
> 
> Then I ran RLDIF using:
> 
> sources '1331+305''
> docalib 1
> gainuse 2
> dopol 1
> pdver 1
> flagver 1
> doband 1
> bpver 1
> spectral 1
> dotv 1
> doapply 1
> 
> I checked the result of 3C286 and all seems to be well although the 
> polarization angle is off by 5 degrees.
> 
> I ran LISTR to check if the Q,U and V flux values were inputted into the 
> SCAN file.  They were not.  If I run PCAL with cparm 0,1 which is to 
> update the source table with the calibrator source Q and U, the values 
> are still not put into the LISTR scan file.  Is there something that I 
> have done wrong with the calibration?  Should I use the PCAL with CPARM 0,1?

You appear to be following the instructions in the EVLA appendix E. 
However, if your data contain only 7 channels they must be earlier VLA 
data.  The SPECTRAL option was really intended only for the EVLA where 
there are many many channels and the polarizers vary a lot with 
frequency.  With SPECTRAL true the source polarizations are written to a 
new CP table not the source table and the polarization solutions are 
written to the new PD table.  POSSM and PRTAB will let you look at these 
2 tables.  However,I suggest that you delete these 2 tables and re-run 
the tasks with SPECTRAL=-1.  PCAL should have CPARM=0,1 in that case 
(the CPARM(2) is ignored with SPECTRAL true).

Eric Greisen