Index: trunk/pswarp/src/pswarpLoopBackground.c
===================================================================
--- trunk/pswarp/src/pswarpLoopBackground.c	(revision 40344)
+++ trunk/pswarp/src/pswarpLoopBackground.c	(revision 40345)
@@ -62,4 +62,5 @@
     pmFPAfileActivate(config->files, true, "PSWARP.BKGMODEL");
 
+    psString refcat = NULL;
     // loop over this section once per input group
     for (int i = 0; i < nInputs; i++) {
@@ -134,4 +135,13 @@
 		    }
 
+		    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);
+		      }
+		    }
+		    
 		    // re-normalize the BKGMODEL pixels by modified astrometry
 		    for (int x = 0; x < readout->image->numCols; x++) {