Index: /trunk/psphot/src/psphotEnsemblePSF.c
===================================================================
--- /trunk/psphot/src/psphotEnsemblePSF.c	(revision 11165)
+++ /trunk/psphot/src/psphotEnsemblePSF.c	(revision 11166)
@@ -120,4 +120,7 @@
     // Ri is the current refSource of interest (sci pixels)
     // Fi is the current fitSource of interest (fit pixels)
+    // note that the sci pixels are real image pixels while the fit pixels are unique for each
+    // fitted source -- they hold the model flux
+
     for (int i = 0; i < fitSources->n; i++) {
         int N = index->data.U32[i];
@@ -177,4 +180,5 @@
         }
     }
+
     psSparseResort (sparse);
     psLogMsg ("psphot.ensemble", PS_LOG_MINUTIA, "built matrix: %f (%d elements)\n", psTimerMark ("psphot"), sparse->Nelem);