[daip] Potential LISTR Bug

[Amanda Kepley]

Hi Eric,

Thanks! I've asked my sys admin to update our AIPS distribution.

Cheers,

Amanda

On Nov 28, 2007, at 3:40 PM, Eric Greisen wrote:

> Found it:
>
> 12506.  November 28, 2007        polarization cal            Eric
>         A bug was discovered that caused polarization calibration to
>         be incorrect when the calibration routines are initialized for
>         a second time.  This is common - LISTR loops over IF with an
>         init each time, SPLIT loops over source, UVPLT reads the data
>         for scaling and checking before rereading for plotting, etc.
>         The result is grossly wrong data because the polarization cal
>         tables do not get reinitialized.  Fortunately, the bug applies
>         only to non-approximate modes and then only when the
>         parallactic angle does not change which would be rare except
>         for equatorial telescopes which have no parallactic angle.
>         Thus WSRT data are almost the only data affected by this bug.
>         Changed DATPOL to init the "old" parallactic angle to an
>         impossible value whenever the source changes.
>
> The MNJ run tomorrow will fix the bug.
>
> Many thanks for your diligence and help.
>
> Eric Greisen

------------------------------------------------------------------------ 
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Amanda Kepley
University of Wisconsin-Madison
Department of Astronomy
Tel: (608) 263-1460
http://www.astro.wisc.edu/~kepley
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