[daip] Re: AIPS question ...

[Eric Greisen]

MIKE HOLLIS writes:

 > In my data cube IMHEAD I have a convolution size of 
 > 1.60" x 1.40"
 > and a pixel size of
 > 0.25" 
 > 
 > I did an IMEAN on that cube and got a beam area of 
 > 40.5 pixels

    My calculator got 40.6 - using the formula
       area = 1.1331 * Bmaj * Bmin (in cells)

 > 
 > I thought that I could convert the IMHEAD convolution size to the beam 
 > area in IMEAN -- but I couldn't.  I assume that the area of an ellipse 
 > would be calculated:
 > 
 > pi x (1.6/0.25) x (1.4/0.25) / 4 = 28.15 pixels
 > 
 > even a rectangle is too small:
 > 
 > (1.6/0.25) x (1.4/0.25) = 35.84 pixels
 > 
 > Any insight would be appreciated ...

      The beam is a Gaussian and this is the integral...

Eric Greisen