[daip] [!8171]: AIPS - REWAY

[Lynn Matthews]

Lynn Matthews updated #8171
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REWAY
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           Ticket ID: 8171
                 URL: https://help.nrao.edu/staff/index.php?/Tickets/Ticket/View/8171
           Full Name: Lynn Matthews
               Email: lmatthew at haystack.mit.edu
             Creator: User
          Department: AIPS Data Reduction
       Staff (Owner): -- Unassigned --
                Type: Issue
              Status: Open
            Priority: Default
                 SLA: NRAO E2E
      Template Group: Default
             Created: 16 March 2016 11:34 PM
             Updated: 16 March 2016 11:34 PM
                 Due: 18 March 2016 11:34 PM (2d 0h 0m)
      Resolution Due: 24 March 2016 11:34 PM (8d 0h 0m)



While investigating the problems that led to my earlier ticket on GETJY, I skipped the use of TYAPL on my data and instead used REWAY to calibrate the weights.

I used the recommended APARM values given in the AIPS Cookbook (APARM=11,30,12,0,10,4). I have used this task before with apparent success, but discovered something that left me worried.

Initially, I forgot to flag my target source. I ran SPLIT and REWAY, then imaged. Afterward, I went back and flagged a bad antenna and repeated these steps. However, IMEAN claimed the noise in my new image was 50% higher. 

I tried a similar experiment on completely unrelated data. I find that if I neglect to apply flags, the resulting image of the REWAYed data clearly looks much noisier than the case where I applied the flags, but IMEAN or IMSTAT will report that the RMS is much smaller and the entire amplitude scale is shifted.

The question I have now is whether REWAY is really giving me the right amplitude scale even when I have flagged carefully.

Lynn


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