[daip] [!16728]: AIPS - Help Explaining Phase Calibrator Plots

[Gregory Walsh]

Gregory Walsh updated #16728
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Help Explaining Phase Calibrator Plots
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           Ticket ID: 16728
                 URL: https://help.nrao.edu/staff/index.php?/Tickets/Ticket/View/16728
                Name: Gregory Walsh
       Email address: gwalsh4758 at gmail.com
             Creator: User
          Department: AIPS Data Reduction
       Staff (Owner): -- Unassigned --
                Type: Issue
              Status: Open
            Priority: Default
                 SLA: NRAO E2E
      Template group: Default
             Created: 06 August 2020 06:49 PM
             Updated: 06 August 2020 06:49 PM
           Reply due: 10 August 2020 06:49 PM (4d 0h 0m)
      Resolution due: 03 May 2023 12:00 AM (999d 5h 11m)

Hello,
I have been calibrating some phase referenced data and am having trouble establishing if my calibration routine, done in AIPS, is satisfactory after looking at amplitude vs. phase plots for the phase calibrators. I would expect to see a tight, circle-esque shape, as this is post-calibration. Instead I see the patterns in the attached image (if you can see the image names, this one is b81script_1018phase_flag.png; if not, it's the really ugly looking image). Note that this data has been flagged with rflag in CASA. The shape and pattern don't seem like anything natural, meaning it would come from my calibration routine, most likely. Do you have any insight into this? Is this a common feature to see?
There are two other things to add. I get nearly the exact same result if I use VLBARUN, and if I average the data over all frequency channels, the pattern disappears and I recover a plot I more expect to see, though still not perfect. The latter applies to both VLBARUN and my calibration routine. I have attached a plot of the averaged data from my calibration routine as well (b81script_1018_128avg_flag.png). Again, this has been flagged.
Sorry if you're not the person to ask about this. I have been banging my head against the wall for a while on this and am scrambling for closure.
Thanks,
Greg 


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