[daip] Project BS077 (Sept.30,1999)

[Peter Kortenkamp]

To: Contact person Geoff Bower


I'm a graduate student at the University of Iowa working with Steve Spangler 
(steven-spangler at uiowa.edu).  I am in the process of reducing the data from 
BS077 and am currently trying to correct for instrumental phase.  I've tried 
using PCCOR but the results show the phase vs frequency plots having sharp 
jumps between channels for many baselines.  As a result I moved on to manual 
phase correction (9.4.8.5 in "Cookbook").  Now when I run POSSM on a section 
of scan from which the fringe fitting sample was taken everything is nice and 
flat and continuous.  However when I run POSSM on a different scan of the same 
calibrator (and of course from the same frequency band) I discontinuous jumps 
between channels again.  In fact the CL table seems to work only for the scan 
from which the fringe fitting sample was taken.  Does this mean the assumption 
of constant instrumental offsets does not hold in this case?  It seems strange 
that instrumentally induced phases would change from one hour to the next.  
Here are a few things I've tried with no success:
-different ref. ant.
-different scan for fringe fitting
-longer solution intervals

Do I need to create a different CL table for each scan?  I should say this is 
my first experience with AIPS and have been at it for only about a month.  No 
doubt it is something simple but any help at all would be appreciated.

Thanks for your time,
Peter Kortenkamp