[daip] [!7188]: AIPS - MBDLY and polarisations

[Eskil Varenius]

Eskil Varenius updated #7188
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MBDLY and polarisations
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           Ticket ID: 7188
                 URL: https://help.nrao.edu/staff/index.php?/Tickets/Ticket/View/7188
           Full Name: Eskil Varenius
               Email: varenius at chalmers.se
             Creator: User
          Department: AIPS Data Reduction
       Staff (Owner): -- Unassigned --
                Type: Issue
              Status: Open
            Priority: Default
                 SLA: NRAO E2E
      Template Group: Default
             Created: 01 September 2015 12:58 PM
             Updated: 01 September 2015 12:58 PM
                 Due: 04 September 2015 12:58 PM (3d 0h 0m)
      Resolution Due: 10 September 2015 12:58 PM (9d 0h 0m)



Dear AIPS support,
I tried running MBDLY with optype 'DISP' after FRING on LOFAR data in AIPS 31DEC15 to correct residual phase curvature due to dispersive delay. I tried first with aparms 0 and found that RR pol seems OK while LL pol has about 180 deg offset and a small residual delay, see attached figures. However, when I set aparm(10)=1 to average it seems to produce good data for both polarisations. I check using POSSM after applying the SN-tables with CLCAL. I find this strange, and although I could just go with setting aparm(10)=1 I wonder at which stage the averaging of the solutions happens. It would be great if you could explain the behaviour. 

To assist investigating this problem I attach two screenshots from POSSM with the two aparm choices applied. I also split out 10 minutes of the original UV-data and uploaded as UVFITS in case you want to try running FRING and MBDLY on the same data:
https://chalmersuniversity.box.com/s/ym8vzbt9o3063bfeta01kpdfpa95u9fm

For FRING, I used the following non-default parameters (ParselTongue syntax) to produce the original SN-table:
fring.solint = 2.0
fring.dparm[2] = 1200 # ns
fring.dparm[3] = 50 # mHz
fring.uvrange = [None, 60, 0] # Use only longest baselines to limit field of view
fring.dofit = [None,] + range(-1, -24, -1) # Do not fit core stations because close and share single clock

Best regards,
Eskil Varenius

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Staff CP:  https://help.nrao.edu/staff
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