[daip] AM649: Juan's bug

[Michael Rupen]

Hi all,
  I re-FILLM'd the AM649 data from 26may00 that we discussed at the VLA
Test meeting yesterday.  I recovered the error in both OLD and TST.
The problem is that the apparent RA and DEC for source 1 -- the *first*
source encountered in the file -- are (incorrectly) set to being the RA and
DEC of source 3, 1331+305.  I tried loading a short time range at the 
beginning of the run, before it even got to source 3, and the problem 
remained.  Since AIPS reads the tape sequentially and stops when it gets to 
the end of the specified time range, I conclude that the problem is with the 
data on tape.  Maybe the antennas had started to slew to 3c286, or were left
there by the last observer, and somehow those coordinates got confused with
those of the new source?  One interesting test I thought of this morning,
but don't have time to do right now, would be to FILLM the data starting
*after* the first scan, to see whether all scans on source 1 (UGC7321) are
affected.  I would bet not, but haven't tried.
  
  Anyhow at this stage I think the ball is in Ken's court...

            Michael

p.s. The relevant archive tapes are XH00056-57-58; actually I only looked
  at the first of these tapes.  The data start in file 12.  I've put the
  tapes back in the archive.