Index: trunk/pswarp/src/pswarpUpdateMetadata.c
===================================================================
--- trunk/pswarp/src/pswarpUpdateMetadata.c	(revision 40344)
+++ trunk/pswarp/src/pswarpUpdateMetadata.c	(revision 40354)
@@ -20,5 +20,12 @@
     bool bilevelAstrometry = psMetadataLookupBool (NULL, skycell->analysis, "ASTROMETRY.BILEVEL");
 
-    psString refcat = psMetadataLookupStr (NULL, output->analysis, "REFERENCE_CATALOG");
+    psString refcat = NULL;
+
+    if ((output)&&(output->analysis)) {    
+      psMetadataItem *refItem = psMetadataLookup(output->analysis, "REFERENCE_CATALOG");
+      if (refItem) {
+	refcat = psMetadataLookupStr (NULL, output->analysis, "REFERENCE_CATALOG");
+      }
+    }
     pmChip *chip;
     while ((chip = pmFPAviewNextChip (view, output, 1)) != NULL) {
@@ -167,5 +174,8 @@
 
     if (refcat) {
-      psMetadataAddStr(output->hdu->header, PS_LIST_TAIL, "PSREFCAT", PS_META_REPLACE, "Reference catalog used for calibration", refcat);
+      if ((output)&&(output->hdu)&&(output->hdu->header)) {
+	psMetadataAddStr(output->hdu->header, PS_LIST_TAIL, "PSREFCAT", PS_META_REPLACE,
+			 "Reference catalog used for calibration", refcat);
+      }
     }