[daip] Error in the UVFIX task in AIPS

[Eric Greisen]

Billie Taylor wrote:
> CALIB dies without any error message and nothing in the previous tasks 
> indicates an error as far as I can tell. There was a single instance 
> where I got an error message during CALIB that said there was no flux 
> for the flux calibrator in the SU table despite the fact that the 
> calibrator plotted successfully in AIPSTV. But I've tried to calibrate 
> the file multiple times and that error hasn't shown again. I've attached 
> a document containing my calibration script from this project, inputs 
> and outputs. I don't see anything unusual in LISTR 'SCAN', but I have 
> been using AIPS less than a year and am not the most familiar with it.

There is a serious issue here - you have only a few visibilities in FQID 
1 for 3C286 (1331+305).  You have more in FQID 2 and you should be able 
to get gain solutions in that bandwidth.  You seem to have no other data 
in that bandwidth however so these solutions do not do you much good.

I suspect the lack of data in FQID 1 was a schedule error that did not 
leave enough time for the long antenna drive (and cable unwrap??). 
CALIB did not die with no error message - it says that it found no 
solutions.  The LISTR output seems to be missing the last character on 
the right but there seems to be only about 20 vis in the FQID 1 scan.
That is not enough to get solutions for 26 antennas.

You can recover some from this using task DFQID to change FQID 2 to FQID 
1.  Then there will be solutions and they will be your best guess as to 
amplitude gains for a flux scale.  But you should be concerned that 
there may be errors in your absolute flux scale which are worse than normal.

ERic Greisen