Index: trunk/psModules/src/objects/pmSourceMoments.c
===================================================================
--- trunk/psModules/src/objects/pmSourceMoments.c	(revision 36856)
+++ trunk/psModules/src/objects/pmSourceMoments.c	(revision 38873)
@@ -409,4 +409,6 @@
 	    float yy = yDiff * y;
 
+	    // the factor of 1/r makes these appropriate for measuring
+	    // \sum r^2 cos(3 theta), sin(3 theta) (psphotImageQuality.c:107)
 	    float xxx = xDiff * xx / r;
 	    float xxy = xDiff * xy / r;
@@ -414,4 +416,6 @@
 	    float yyy = yDiff * yy / r;
 
+	    // the factor of 1/r^2 makes these appropriate for measuring
+	    // \sum r^2 cos(4 theta), sin(4 theta) (psphotImageQuality.c:107)
 	    float xxxx = xDiff * xxx / r2;
 	    float xxxy = xDiff * xxy / r2;