[daip] [!4940]: aips - JMFIT and -ive zero level

[Michael Bietenholz]

Michael Bietenholz updated #4940
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              Status: Open (was: Closed)

JMFIT and -ive zero level
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           Ticket ID: 4940
                 URL: https://help.nrao.edu/staff/index.php?/Tickets/Ticket/View/4940
           Full Name: Michael Bietenholz
               Email: mbieten at yorku.ca
             Creator: User
          Department: AIPS Data Processing
       Staff (Owner): Eric Greisen
                Type: Issue
              Status: Open
            Priority: Default
      Template Group: Default
             Created: 20 May 2014 03:01 PM
             Updated: 11 June 2014 04:42 PM



JMFIT seems to work now - thanks! MAXFIT seems to have a similar issue. I think if the highest point in its search window is in fact negative, MAXFIT says "FIT FAILS".  However on an image which is identical but for the addition of a constant brightness, so that the highest point is now +ive, it finds the maximum correctly.

(ie. on the test image attached earlier "test-ive.fits", which has a positive-going extremum near PIXXY=6,6, but the actual brightness there is -5.1 mJy/bm, MAXFIT fails w/ PIXXY=6,6; IMSI=3;  If I use COMB with INNAM=IN2NAM="test-ive.fits"; OPCO='SUM'; APARM=0.5,0.5,7e-3 to shift the zero level enough to make the pixxy=6,6 point +ive, MAXFIT works fine).

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