Though we were not very successful in determining if rays came from specific regions of the moon via the Layout, another strategically placed Detector Rectangle could prove to be more useful.  Insert a Detector Rectangle as Object 12 in the NSC Editor.  Define the Detector Rectangle with the following parameters:

Y Position: 1.0
Z Position: -9.0
Tilt About X: 5.0
X Half Width: 6.1
Y Half Width: 6.1
# X Pixels: 50
# Y Pixels: 50

Leave all other parameters as the defualt.  Note that this Detector Rectangle is placed directly in front of the moon.  This way, using the filter string capabilities once again, we can better visualize the distribution of those rays which originate from the moon and hit the camera.  Once the new Detector Rectangle is defined, open a new Detector Viewer to view Detector Object 12 (remember, the settings must be set correctly to show this). 

If we perform a new ray trace and save the rays to a new database name, such as "Stray Light_Telescope_1A.ZRD," we can see the initial ray distribution on the newly defined detector:



Since no current filter is applied, the irradiance distribution on this detector includes rays from both sources.  Again, we are only concerned with rays which originate from the moon AND reach the detector.  Therefore, let's apply the following filter to Detector Object 12:



Once the filtered data is processed and displayed, it is much easier to observe the distribution of rays from the moon which actually reach the detector plane.  It is apparent that undesired, stray rays at the detector plane, do indeed originate from "preferential" regions of the moon.  These regions are highlighted in the Detector Viewer below.  This information may be useful in determining which of the various stray light reduction techniques could be used to reduce the undesired light from the moon.