[daip] question about aips tasks

[Hiroko Shinnaga]

Dear Sir:

   I have a couple of questions about AIPS tasks.
I have following symptoms and I would like to judge
where these symptoms come from (either software or
data itself).

1. I found a disagreement between LISTR statements
   and the plot made with VPLOT for a data set.
   The situation is as follows.  Although LISTR reports
   data on some specific object were taken during some
   specific time periods, the plot created by VPLOT is
   shifted about 15 min from the LISTR statements. Namely,
   the observing periods has a time lag roughly about 15
   minutes between LISTR and VPLOT.  I checked the observing
   script which was run during the period.  Comparing with
   the script, it seems that LISTR output looks correct
   and VPLOT looks not correct.  With UVPLOT, the
   plot of time vs. phase (or amp) agrees with
   LISTR results.  So, it seems VPLOT creates wrong plot.
   I tried to specify time using the BPARM option.  However,
   the results were the same.  Could you let me know
   possible reasons why this is happening?  Have you
   seen this problem before?

2.  Using the same data set, when I set xinc as 3
    or 2 on vplot, I couldn't see almost any point on many
    baselines (such as antenna 1, 8, 11, 17, 18,19,
    etc).  However, when I set xinc as 1, I could see
    all the data points including baselines of antenna
    1 etc, which looked missing using xinc = 2 or 3.
    Could you let me know possible reasons why this is
    happening?

3.  Above two issues are  happening only on a specific
     data set. I created this AIPS data file using
     multiple(four) tape files with FILLM.  For the
     other data set that I created from one tape file
     with FILLM, with the same options, I didn't have
     the above problems.  Do you think these are related?
     (Please note that both data sets were taken using
     fast switching.  I don't know if these are related.
     But just as a info. )

   I would like to appreciate your response soon,
if possible.  I have my next VLA run this week
Thursday.  In case the data itself have some problem,
I need to investigate my script to avoid these issues.

   Hope to hear from you.  Thank you very much for
your help.


Hiroko

-- 
Hiroko Shinnaga, Staff Scientist    email: shinnaga at submm.calteh.edu
Caltech Submillimeter Observatory   Phone: 808-935-1909
California Institute of Technology  Fax:   808-961-6273
111 Nowelo St., Hilo, HI 96720 USA  http://puuoo.submm.caltech.edu/~hs