Index: trunk/psphot/src/psphotEnsemblePSF.c
===================================================================
--- trunk/psphot/src/psphotEnsemblePSF.c	(revision 6900)
+++ trunk/psphot/src/psphotEnsemblePSF.c	(revision 6949)
@@ -29,5 +29,5 @@
     psArray  *models = psArrayAlloc (sources->n);
     psVector *index  = psVectorAlloc (sources->n, PS_TYPE_U32);
-    models->n = index->n = 0;
+    // DROP models->n = index->n = 0;
 
     // option to limit analysis to a specific region
@@ -170,5 +170,5 @@
 
     psSparseConstraint constraint;
-    constraint.paramMin   = 0;
+    constraint.paramMin   = 0.0;
     constraint.paramMax   = 1e8;
     constraint.paramDelta = 1e8;
@@ -191,4 +191,7 @@
 
 	// assign linearly-fitted normalization
+	if (isnan(norm->data.F32[i])) {
+	    psAbort ("psphot", "ensemble source is nan");
+	}
 	Fi->modelPSF->params->data.F32[1] = norm->data.F32[i];
 	Fi->modelPSF->dparams->data.F32[1] = sqrt(sqrt(2) * norm->data.F32[i] / (sparse->Bfj->data.F32[i] * weight->data.F32[i]));