[daip] [!7729]: AIPS - Large phsae errors with an antenna having different total bandwidth

[Amy Mioduszewski]

Amy Mioduszewski updated #7729
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Large phsae errors with an antenna having different total bandwidth
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           Ticket ID: 7729
                 URL: https://help.nrao.edu/staff/index.php?/Tickets/Ticket/View/7729
           Full Name: Jae-Young Kim
               Email: jykim at astro.snu.ac.kr
             Creator: User
          Department: AIPS Data Reduction
       Staff (Owner): -- Unassigned --
                Type: Issue
              Status: Open
            Priority: Default
                 SLA: NRAO E2E
      Template Group: Default
             Created: 14 December 2015 09:34 AM
             Updated: 16 December 2015 09:37 AM
      Resolution Due: 22 December 2015 09:34 AM (5d 23h 56m)



Dear Jae-Young,

I see a couple things you can try to diagnose this.  From my understanding of things, the fact that PdBI only has 8 IFs shouldn't be an issue.  CALIB treats each IF as an individual.  There does seem to be a residual delay on PdBI after fringe fitting and PdBI seems to be have higher sensitivity than the other antennas.  So it looks like PdBI is a poorly calibrated high weight antenna.   So some options in CALIB you should explore:
1) downweight PdBI significantly using ANTWT
2) First run CALIB on all the antennas except PdBI in until you are happy with the calibration.  Then apply the calibration to the dataset that includes PdBI (applying the calibration without deleting PdBI is slightly complicated, I can go into more detail if you want to go this route) and then use ANTENNAS, DOFIT and possibly ANTUSE to just calibrate PdBI using all the other antennas. 

I would recommend trying #1 first which is much easier.  Although the above begs the question of why PdBI is so poorly calibrated.  I am a little confused about how you did the the manual phase cal.  Did you do it in several steps because you could not find a scan that had all the antennas in it?



Amy Mioduszewski
NRAO

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