Index: trunk/psphot/src/psphotFitSourcesLinearStack.c
===================================================================
--- trunk/psphot/src/psphotFitSourcesLinearStack.c	(revision 31154)
+++ trunk/psphot/src/psphotFitSourcesLinearStack.c	(revision 31452)
@@ -69,4 +69,17 @@
             if (!pmSourceCacheModel (source, maskVal)) continue;
           }
+
+	  // check the integral of the model : is it large enough?
+	  float modelSum = 0.0;
+	  for (int iy = 0; iy < source->modelFlux->numRows; iy++) {
+	      for (int ix = 0; ix < source->modelFlux->numCols; ix++) {
+		  modelSum += source->modelFlux->data.F32[iy][ix];
+	      }
+	  }
+	  if (modelSum < 0.5) continue; // skip sources with no model constraint (somewhat arbitrary limit)
+	  if (modelSum < 0.8) {
+	      fprintf (stderr, "low-sig model @ %f, %f (%f sum, %f peak)\n",
+		       source->peak->xf, source->peak->yf, modelSum, source->peak->rawFlux);
+	  }
 
           source->mode |= PM_SOURCE_MODE_LINEAR_FIT;