[daip] Initial Calibration

[Eric Greisen]

Ed Butcher writes:
 > 
 > My name is Ed Butcher and I've just finished my third year studying physics
 > at the University of Waterloo. This summer I'm doing research here under the
 > supervision of Mike Fich in the astrophysics department. Right now I'm using
 > AIPS to image observations of HII regions obtained with the VLA. This is the
 > first time I have used AIPS.

     In general, your advisor should be dealing with your questions
first.  We should be a resort only when it is fairly clear that the
software has an error or is incomprehensible to both of you.

 > 
 > I have been following the directions in the AIPS Cookbook regarding initial
 > calibration of the data, and having completed the procedure for the first
 > set of observations, it was suggested I contact you to verify the results. I
 > was concerned since the phases of many of the calibrators seem to vary quite
 > a bit from zero after calibration.
 > 
 > I have attached a text file containing some sample MATX output from LISTR
 > for various calibrators. Do the results seem reasonable? If not, what might
 > I be doing wrong?
 > 

It is hard to tell what has gone wrong.  It would appear that you have
a good phase calibration at the beginning and a progressively worse one
the rest of the way.  What did the SN table contain, what did the CL
table contain?  Did you apply the cal data from only the first
calibrator and use that for all times?  Check your inputs to CLCAL in
particular.

Eric Greisen