[Vlavlbausers] Error in AIPS task FILLM in handling opacities

[Data Analysts]

To: All VLA users
Subject: Error in AIPS task FILLM in handling opacities

Dear colleague,

The 31DEC08 (TST) version of FILLM had a problem with its handling of a
newly available band code in an observation.  In the period from September
13 to October 20, 2008, FILLM was under the impression that the data it
was handling were in the band of the new scan rather than the band of the
scan it still had to finish writing.  If your observations were all at
one band, then there is no problem.  If there were band changes during
the observation then the last record of each scan in CL table version
1 will have opacities and antenna gains calculated for the (incorrect)
band of the next scan.  This can make a significant error if one of the
bands is at relatively high frequency.  This error can be repaired most
simply by deleting all CL tables including version 1 and running INDXR,
or it can be repaired by using a version of FILLM from a midnight job
run after October 20, 2008.

Please contact daip at nrao.edu if you have any further questions about
the quality of your data.

Claire Chandler
Deputy Assistant Director for Science, NM Operations