It is useful to compute the radial light distribution in a discrete source for a number of reasons.

%  ellradius.sh 400 400 120.0 200.0 20.0 0.65 20.0   
 arg1 - X dimension of output image
 arg2 - Y dimension of output image
 arg3 - X center in pixels 
 arg4 - Y center in pixels 
 arg5 - circle radius (asemi in pixels) 
 arg6 - axis ratio (b/a) 
 arg7 - pa in degrees (GALPHOT convention)

FIGURE 1: Radius maps from ellradius. The command line used to generate the image is just above the ellipse. A bold black ds9 ellipse region has been plotted to verify the size and orientation of the ellipse. At the bottom are the ds9 parameters needed for this ellipse region plot (aside from the center). Recall that when the X component is the semi-major axis, then the angle value is measure from the +X axis in a counter-clockwise (CCW) direction in units of degrees.