[daip] Request for an amplitude gain clip in CALIB

[R. Craig Walker]

While iterating CALIB and IMAGR to make VLBI images, I often get a small
but noticable number of very bad gains, which in turn creates points with
amplitudes that are very far off - usually high which is the more damaging
case.  For example, for one antenna, I just had a case with all gains less
than about 1.5 (mostly near 1.0), but one at 20.  Getting rid of the
effects of such solutions is painful, especially when doing many
iterations.  And it is frustrating to have what looked like a clean data
set going in develop a number of wild points in self-calibration.  These
gains don't always get flagged by the current flagging options which pay
attention to solution rms's and closure offsets.

My suggestion is that the user be able to request a maximum (and minimum)
allowed gain, perhaps on a per-antenna basis.  If a solution comes in over
(under) that value, it will be treated as a failed solution having the
effect of flagging the data (unless the table is smoothed and reapplied).

Cheers,

Craig


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    R. Craig Walker            Array Operations Center
    cwalker at nrao.edu           National Radio Astronomy Observatory
    Phone  505 835 7247        P. O. Box O
    Fax    505 835 7027        Socorro NM 87801   USA
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