Index: trunk/psphot/src/psphotRadiusChecks.c
===================================================================
--- trunk/psphot/src/psphotRadiusChecks.c	(revision 10140)
+++ trunk/psphot/src/psphotRadiusChecks.c	(revision 11174)
@@ -26,10 +26,15 @@
 {
     pmMoments *moments = source->moments;
-    if (moments == NULL) return false;
+    // do we have a better value for the sky noise level?
+    // not really...
 
     // set the fit radius based on the object flux limit and the model
     float radiusFit = PSF_FIT_RADIUS;
     if (radiusFit <= 0) {		// use fixed radius
-	radiusFit = modelRadiusPSF(model->params, PSF_FIT_NSIGMA*moments->dSky);
+	if (moments == NULL) {
+	    radiusFit = modelRadiusPSF(model->params, PSF_FIT_NSIGMA*moments->dSky);
+	} else {
+	    radiusFit = modelRadiusPSF(model->params, 1.0);
+	}
     }
     model->radiusFit = (RADIUS_TYPE)(radiusFit + PSF_FIT_PADDING);