[daip] vla data trouble shooting (fwd)

[Eric Greisen]

 > I recently did a VLA HI experiment which uses two separate tunings.
 > I had 2 different calibrators for each tuning (two different targets
 > as well).  To my surprise, FILLM assigned FREQID 1 to both calibrators and
 > source 1 while the source 2 is assigned FREQID 2.  

    Your grammar here makes it sound as if you had 2 calibrators and 2
targets at frequency 1 and 2 more of each at frequency 2.  Later
wording suggests that in fact you meant 1 of each at each frequency,
which I will now assume.

 > 
 > First of all, how would this happen?  I verified that my observe
 > file was set up correctly.  Is there a parameter in FILLM that would
 > sort this out more carefully?  I used different qualifers to deal with
 > this during the FILLM process, but FILLM does not use qualifiers.

     I assume that you made an error in setup - or the on-line system
did which is unlikely.  FILLM looks at the frequency of the data as
recorded by the on-line system and does its assigning on that basis.
Therefore FILLM was told that both calibrators and target 1 were at
one frequency and target 2 was at another substantially different.

There is an option in FILLM to have all observations treated as one
frequency ID.  Having done that you could use UVCOP to separate the
two portions of the data into two separate files.

 > 
 > I thought I might able to fool
 > AIPS to apply the gain solution from the calibrator 2 (FREQID 1)
 > to source 2 (FREQID 2), but CLCAL knows something about FREQID.  
 > I thought I could manually change the
 > FREQID entry in the FQ table or SU table, but doing so does not
 > seem so obvious because entries in these tables are not so simple.
 > Could I edit something in the SN table?

   There is a FREQID column in the SN table - that could be TABED
changed to have value 2 (or 0 meaning all).

Eric Greisen

 > 
 > Have you ever had this kind of problem before?  Any suggests on
 > solving this problem?  Thanks a million!
 > 
 > 
 > 					-- Min
 > 
 > -----------
 > 
 > Min S. Yun				e-mail: myun at astro.umass.edu
 > Associate Professor			phone:  (413) 545-2215
 > Astronomy Department			FAX:    (413) 545-4223
 > University of Massachusetts             http://www.astro.umass.edu/~myun
 > Amherst, MA 01003
 > 
 > 
 > 
 > 
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