Index: trunk/psphot/src/psphotGuessModels.c
===================================================================
--- trunk/psphot/src/psphotGuessModels.c	(revision 13343)
+++ trunk/psphot/src/psphotGuessModels.c	(revision 13569)
@@ -56,4 +56,23 @@
     // set PSF parameters for this model (apply 2D shape model)
     pmModel *modelPSF = pmModelFromPSF (modelEXT, psf);
+    if (modelPSF == NULL) {
+	psError(PSPHOT_ERR_PSF, false,
+		"Failed to determine PSF model at r,c = (%d,%d); trying centre of image",
+		source->peak->y, source->peak->x);
+	//
+	// Try the centre of the image
+	//
+	modelEXT->params->data.F32[PM_PAR_XPOS] = 0.5*readout->image->numCols;
+	modelEXT->params->data.F32[PM_PAR_YPOS] = 0.5*readout->image->numRows;
+	modelPSF = pmModelFromPSF (modelEXT, psf);
+	if (modelPSF == NULL) {
+	    psError(PSPHOT_ERR_PSF, false,
+		    "Failed to determine PSF model at centre of image");
+	    psFree(modelEXT);
+	    return false;
+	}
+
+	source->mode |= PM_SOURCE_MODE_BADPSF;
+    }
     psFree (modelEXT);