Index: trunk/psphot/src/psphotApResid.c
===================================================================
--- trunk/psphot/src/psphotApResid.c	(revision 6379)
+++ trunk/psphot/src/psphotApResid.c	(revision 6495)
@@ -11,4 +11,7 @@
 
     psTimerStart ("psphot");
+
+    // S/N limit to perform full non-linear fits
+    float FIT_SN_LIM = psMetadataLookupF32 (&status, config, "FULL_FIT_SN_LIM");
 
     // measure the aperture loss as a function of radius for PSF
@@ -37,4 +40,7 @@
 	if (source->mode &  PM_SOURCE_POOR) continue;
 
+	// XXX tune independently?
+	if (source->moments->SN < 2*FIT_SN_LIM) continue;
+
 	// get uncorrected magnitudes in scaled apertures
 	model = pmSourceMagnitudes (source, NULL, 0);