[daip] [!15130]: AIPS - Issue: after running VLBAAMP (ACSCL) amplitude goes to zero

[Cristiana Spingola]

Cristiana Spingola updated #15130
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Issue: after running VLBAAMP (ACSCL) amplitude goes to zero
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           Ticket ID: 15130
                 URL: https://help.nrao.edu/staff/index.php?/Tickets/Ticket/View/15130
                Name: Cristiana Spingola
       Email address: spingola at astro.rug.nl
             Creator: User
          Department: AIPS Data Reduction
       Staff (Owner): -- Unassigned --
                Type: Issue
              Status: Open
            Priority: Default
                 SLA: NRAO E2E
      Template group: Default
             Created: 03 December 2019 01:39 PM
             Updated: 03 December 2019 01:39 PM
           Reply due: 05 December 2019 01:39 PM (2d 0h 0m)
      Resolution due: 29 August 2022 12:00 AM (999d 10h 21m)

Hi,
I am using AIPS 31Dec16 to reduce VLBA data at 43 GHz. The experiment includes almost 20 observations at 43 GHz, but I have issues for about half of the observations when running VLBAAMP, in particular ACSCL. After running ACSCL, the amplitudes of all baselines go to zero (see plots of POSSM attached, where CL4 is obtained before ACSCL and CL5 is obtained after ACSCL). So, I tried to run separately ACSCL and APCAL. I tested different values for the parameters in ACSCL, trying small and large solution intervals and/or using only some scans, but it did not help. Moreover, the mean values of the SN table produced by ACSCL are expected to be ~1, while in my case they are very small (see plot attached). Also, I have ran the bandpass calibration before ACSCL and used BP table.  
I found out that alternatively one may use CLCOR to force the ACSCL solutions to be close to 1, but I did not find an explanation about how to set correctly the parameters for applying this correction. Could you please tell me how should I set them?

Thanks and best regards,
Cristiana


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