[daip] [!5480]: aips - CVEL AIPS 2

[Carolina Rodriguez]

Carolina Rodriguez updated #5480
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              Status: Open (was: Closed)

CVEL AIPS 2
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           Ticket ID: 5480
                 URL: https://help.nrao.edu/staff/index.php?/Tickets/Ticket/View/5480
           Full Name: Carolina Rodriguez
               Email: ca.rodriguez at crya.unam.mx
             Creator: User
          Department: AIPS Data Processing
       Staff (Owner): Eric Greisen
                Type: Issue
              Status: Open
            Priority: Default
      Template Group: Default
             Created: 11 September 2014 04:45 PM
             Updated: 22 October 2014 05:44 PM



Last attempt:
I made a mistake and sent you the wrong file.
These are the updated questions, perhaps here I explain better my doubts.



The questions are:

- Why the velocity is still the same as in the observing plan?
  Shouldn't the pixel with -17.6 km/s be offset from pixel 64
  by either 3.3 or 1.9 pixels?

- Why are the frequencies in pixel 64 (from imagr/imean) 
  different from the values predicted by DOPSET?
  If pixel 64 was observed at the sky frequency given in the 
  observe file, then that can't be changed, so pixel 64 should
  always have the same frequency.
  But the LSR velocity that corresponds to that sky freq will 
  depend on the day/time when the observation was made.  
  So the velocity label assigned to each channel WILL change
  (and should NOT always be the same in channel 64).

- From reading the instructions for APARM in CVEL, it seems
  that we're assigning -17.6 km/s to channel 64, which doesn't
  seem right.  But unless we use aparm(2) = 64 +- 3.3 or 1.9
  (and fractional channel numbers doesn't seem reasonable) 
  how would we tell CVEL what pixel should have the -17.6 velo?
  Are we using CVEL improperly?

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