[daip] Re: FREQID question

[Eric Greisen]

Mark Reid writes:

 >       I just FITLD'ed some VLBA observaitons of OH masers
 > and ended up with 5 FREQIDs for the 5 different observing
 > frequencies.  The frequency differences are very small
 > (100 kHz) and so I really don't want any distinction 
 > among the different sources when I calibrate.
 > 
 >       From my experience, having different FREQIDs will lead 
 > to real problems later as many AIPS tasks do not allow one to
 > ignore FREQIDs.  For example, one cannot simply set FREQID=-1
 > and have all tasks process all data.
 > 
 >       I tried running FITLD again, setting a FREQSEL and
 > FRQTOL to include all the source frequencies, but it still
 > said that it was still outputting different FREQIDs.
 > I also looked into using UVCOP to force an output file
 > with all FREQIDs set to 1, but I couldn't seem to get
 > this to happen.
 > 
 >       Is there any way to get out of this mess?
 > 

     I am tired at the moment and may be missing something, but if you
declare the frequencies to be the same it will be hard to label
velocities correctly later.  You are right that once separated, they
are hard to bring together.  If you really need the cal from frequncy
 1 to apply to frequency 2, you can run TABED to make the calibrations
of FREQID n be FREQID 0.  Then all FREQIDs will use those
calibrations.  The separation into separate FREQIDs is done at the
correlator not by AIPS - if you think the correlator has made too
many, let me know the Project ID, time range, correlator job # and we
can check.  Send me the LISTR 'SCAN' listing so that I can see what
you have.  It would be possible to make a version of MATCH that
renumbered all obs at FREQID 1 but that may really not be what you
want.

Eric