Index: trunk/pswarp/src/pswarpLoopBackground.c
===================================================================
--- trunk/pswarp/src/pswarpLoopBackground.c	(revision 40345)
+++ trunk/pswarp/src/pswarpLoopBackground.c	(revision 40354)
@@ -137,8 +137,13 @@
 		    if (astrom != input) {
 		      pmReadout *astromRO = pmFPAviewThisReadout(view, astrom->fpa); // Readout for astrometry
-		      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);
+			  }
+			}
 		      }
 		    }