[daip] Incomplete CL tables.

[R. Craig Walker]

I wasted most of my available time today trying to figure this out so I
thought I'd bring it up.  I have a file, the result of a DBCON of two
MULTI source data sets.  Both data sets were made from the same original
data set, one with SPLAT, and one with SPLIT (to single source) - UVFIX -
MULTI.  The latter file does not have a CL table.  The DBCON file has a CL
table, but only with entries from the source that came via the single
source file - ie not the sources that came with the SPLAT file which has a
CL table.  The result of this odd situation is that the scans (sources)
that do not appear in the CL table do not register at all, with no
warnings, to programs that use the calibration capabilities, such as UVPRT
even with DOCALIB=-1.   Programs that do not use calibration, such as
PRTUV, see those scans.  I was going nuts trying to figure out why VPLOT
etc would not see data that LISTR (OPTYPE='SCAN') and PRTUV could see.  I
even ran INDXR.  It found all the scans, but it did not recreate CL table
1.

Finally I tried deleting the NX and CL tables and and running INDXR in the
mode to create the CL table.  There were massive numbers of complaints
about missing IM table entries, but it ran and now I can see the scans. 
Since all previous calibrations got applied in SPLAT and SPLIT and all I
need is the FRING SN table, I think I am now ok.

In case you are wondering how I got here - it is the result of wanting all
sources in a file on which to run FRING to give an input SN table for a
rate based DELZN.  Unfortunately one of the sources, the one with by far
the most data, was correlated with a 1 arcsecond offset in the position,
so I needed to run UVFIX on it first.  But UVFIX only claims to work on
single source data sets.  I could have tried with CLCOR, but I already
wasted another day thanks to using a file produced by someone else where a
CLCOR position shift had been done, and then the CL tables deleted.  The
modified (unknown to me) SU table position was good, but the fringes were
clearly for the offset position.  Massive confusion.

Anyway, I think I now have a workaround.  I'm not sure if there is a way
to keep others out of this trap, but thought I'd let you know about it.

Cheers,

Craig



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    R. Craig Walker            Array Operations Center
    cwalker at nrao.edu           National Radio Astronomy Observatory
    Phone  575 835 7247        P. O. Box O
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