[daip] [!6921]: AIPS - VLBA continuum data reduction----three questions

[Hui Zhang]

Hui Zhang updated #6921
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              Status: Open (was: Response Overdue)

VLBA continuum data reduction----three questions
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           Ticket ID: 6921
                 URL: https://help.nrao.edu/staff/index.php?/Tickets/Ticket/View/6921



HI, Amy, 
       Thank you for your reply very much. 
        I tried many times to process the data, and now I think the result is acceptable. The parameters of 'fringe' are shown in 
the file named 'fring_para.txt', and the parameters of calibration are shown in the file named 'clcal_para.txt'. It reported that it 
found 4043 good solutions and failed on 973 solutions. But there was still one thing puzzled me. When I used 'possm' to check
the CL# 8, created by the global  fringe search, I find there was no data in some baselines, like in figure '0219+428_cl8.png'.
Why there was no data on these baselines, but most of the baselines are good on other scans for this phase reference source (0219+428)? Is is because the solutions are not fond on these baselines?

       I have another question, please check the file 'GC441_phase_calibrator.png' (from another data with phase referencing experiment). This source is a phase calibrator, the phases were distributed in the whole range -180 to 180 degrees, almost uniform in this range, 
so some one told me that we can not use this calibrator to do the global fringe fitting to remove the frequency- and time-dependent 
phase errors. He thought the phases of phase calibrator should have some obviouse trends, then we can calculate the phase 
delay residual and phase delay residual rate. **** Is that true? ****  Why the phases are so bad for this phase calibrator? 
Because this data has been published, I think the author must have a method to reduce this data. 

      I really thank you very much, and thank NRAO has such good platform for our new learners.

Best Regard,
Hui Zhang

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