Index: trunk/pswarp/src/pswarpLoop.c
===================================================================
--- trunk/pswarp/src/pswarpLoop.c	(revision 40344)
+++ trunk/pswarp/src/pswarpLoop.c	(revision 40354)
@@ -124,9 +124,14 @@
 
 			// Determine the reference catalog used
-			if (!refcat) {
-			  refcat = psMetadataLookupStr(NULL, astromRO->parent->parent->hdu->header, "PSREFCAT");
-			  psMetadataAddStr(output->fpa->analysis, PS_LIST_TAIL, "REFERENCE_CATALOG", PS_META_REPLACE, "Reference catalog used for calibration.", refcat);
+			if ((!refcat)&&(astromRO)) {
+			  if ((astromRO->parent->parent->hdu->header)&&(output->fpa->analysis)) {
+			    psMetadataItem *refItem = psMetadataLookup(astromRO->parent->parent->hdu->header, "PSREFCAT");
+			    if (refItem) {
+			      refcat = psMetadataLookupStr(NULL, astromRO->parent->parent->hdu->header, "PSREFCAT");
+			      psMetadataAddStr(output->fpa->analysis, PS_LIST_TAIL, "REFERENCE_CATALOG", PS_META_REPLACE,
+					       "Reference catalog used for calibration.", refcat);
+			    }
+			  }
 			}
-
 			
 		    }