[daip] [!9210]: AIPS - Beam Area calculation

[Scott Hyman]

Scott Hyman updated #9210
-------------------------

 Beam Area calculation
----------------------

           Ticket ID: 9210
                 URL: https://help.nrao.edu/staff/index.php?/Tickets/Ticket/View/9210
           Full Name: Scott Hyman
               Email: shyman at sbc.edu
             Creator: User
          Department: AIPS Data Reduction
       Staff (Owner): -- Unassigned --
                Type: Issue
              Status: Open
            Priority: Default
                 SLA: NRAO E2E
      Template Group: Default
             Created: 27 October 2016 07:08 PM
             Updated: 27 October 2016 07:08 PM
                 Due: 31 October 2016 07:08 PM (4d 0h 0m)
      Resolution Due: 04 November 2016 07:08 PM (8d 0h 0m)



Hi Eric,

IMSTAT and TVSTAT output the "beam area" in pixels.  However, if the beam sizes in the header of the image are FWHMs, then I can't reproduce the IMSTAT beam areas.  E.g., for a 20" x 20" beam in the header of an image with 1" x 1" pixels, shouldn't the beam area just be pi*(20/2)^2 = 314 pixels?  But IMSTAT returns 453 pixels.  However, if the 20" in the header is interpreted as 1 sigma instead of the FWHM, then converting it to FWHM, the area would be pi*(20*2.355/4)^2 = 436 pixels.  I must be missing something.

Scott

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