Index: trunk/psModules/src/concepts/pmConcepts.c
===================================================================
--- trunk/psModules/src/concepts/pmConcepts.c	(revision 26923)
+++ trunk/psModules/src/concepts/pmConcepts.c	(revision 26964)
@@ -292,5 +292,5 @@
         conceptRegisterF32("FPA.FOCUS", "Telescope focus", NULL, NULL, NULL, false, PM_FPA_LEVEL_FPA);
         conceptRegisterF32("FPA.AIRMASS", "Airmass at boresight", NULL, NULL, NULL, false, PM_FPA_LEVEL_FPA);
-	// XXX p_pmConceptParse_FPA_FILTER -> p_pmConceptParse_FPA_FILTERID (and Format as well)?
+        // XXX p_pmConceptParse_FPA_FILTER -> p_pmConceptParse_FPA_FILTERID (and Format as well)?
         conceptRegisterStr("FPA.FILTERID", "Filter used (parsed, abstract name)", p_pmConceptParse_FPA_FILTER, p_pmConceptFormat_FPA_FILTER, NULL, false, PM_FPA_LEVEL_FPA);
         conceptRegisterStr("FPA.FILTER", "Filter used (instrument name)", NULL, NULL, NULL, false, PM_FPA_LEVEL_FPA);
@@ -334,7 +334,8 @@
         conceptRegisterF32("FPA.TELTEMP.EXTRA", "Telescope Temperatures: extra", p_pmConceptParse_TELTEMPS, NULL, NULL, false, PM_FPA_LEVEL_FPA);
         conceptRegisterF32("FPA.PON.TIME", "Power On Time", NULL, NULL, NULL, false, PM_FPA_LEVEL_FPA);
-	conceptRegisterS32("FPA.BURNTOOL.APPLIED", "[T=applied] Burn streaks applied to image data", p_pmConceptParse_BTOOLAPP,p_pmConceptFormat_BTOOLAPP,NULL,false,PM_FPA_LEVEL_FPA);
-	//	conceptRegisterBool("FPA.BURNTOOL.APPLIED", "Status of burntool processing", NULL, NULL, NULL, false, PM_FPA_LEVEL_FPA);
+        conceptRegisterS32("FPA.BURNTOOL.APPLIED", "[T=applied] Burn streaks applied to image data", p_pmConceptParse_BTOOLAPP,p_pmConceptFormat_BTOOLAPP,NULL,false,PM_FPA_LEVEL_FPA);
+        //      conceptRegisterBool("FPA.BURNTOOL.APPLIED", "Status of burntool processing", NULL, NULL, NULL, false, PM_FPA_LEVEL_FPA);
         conceptRegisterF32("FPA.EXPOSURE", "Exposure time (sec)", NULL, NULL, NULL, false, PM_FPA_LEVEL_FPA);
+        conceptRegisterF32("FPA.ZP", "Magnitude zero point", NULL, NULL, NULL, false, PM_FPA_LEVEL_FPA);
     }
     if (!conceptsChip) {
Index: trunk/psModules/src/concepts/pmConceptsAverage.c
===================================================================
--- trunk/psModules/src/concepts/pmConceptsAverage.c	(revision 26923)
+++ trunk/psModules/src/concepts/pmConceptsAverage.c	(revision 26964)
@@ -36,4 +36,5 @@
 
     double time      = 0.0;             // Time of observation
+    double zp        = 0.0;             // Zero point
     psTimeType timeSys = 0;             // Time system
     char *filter     = NULL;            // Filter
@@ -63,4 +64,7 @@
         psTimeConvert(fpaTime, PS_TIME_TAI);
         time       += psTimeToMJD(fpaTime);
+
+        zp += psMetadataLookupF32(NULL, fpa->concepts, "FPA.ZP");
+
         if (num == 1) {
             timeSys = psMetadataLookupS32(NULL, fpa->concepts, "FPA.TIMESYS");
@@ -85,4 +89,5 @@
 
     time /= (double)num;
+    zp /= (double)num;
 
     MD_UPDATE(target->concepts, "FPA.TIMESYS", S32, timeSys);
@@ -92,4 +97,5 @@
     MD_UPDATE_STR(target->concepts, "FPA.INSTRUMENT", instrument);
     MD_UPDATE_STR(target->concepts, "FPA.DETECTOR", detector);
+    MD_UPDATE(target->concepts, "FPA.ZP", F32, zp);
 
     // FPA.TIME needs special care
Index: trunk/psModules/src/objects/pmSourceIO_CMF_PS1_V1.c
===================================================================
--- trunk/psModules/src/objects/pmSourceIO_CMF_PS1_V1.c	(revision 26923)
+++ trunk/psModules/src/objects/pmSourceIO_CMF_PS1_V1.c	(revision 26964)
@@ -69,9 +69,12 @@
     float magOffset = NAN;
     float exptime   = psMetadataLookupF32 (&status1, fpa->concepts, "FPA.EXPOSURE");
-    float zeropt    = psMetadataLookupF32 (&status2, imageHeader, "ZPT_OBS");
-    float zeroptErr = psMetadataLookupF32 (&status2, imageHeader, "ZPT_ERR");
+    float zeropt    = psMetadataLookupF32(&status2, fpa->concepts, "FPA.ZP");
+    if (!isfinite(zeropt)) {
+        zeropt    = psMetadataLookupF32 (&status2, imageHeader, "ZPT_OBS");
+    }
     if (status1 && status2 && (exptime > 0.0)) {
         magOffset = zeropt + 2.5*log10(exptime);
     }
+    float zeroptErr = psMetadataLookupF32 (&status2, imageHeader, "ZPT_ERR");
 
     // if the sequence is defined, write these in seq order; otherwise
@@ -477,5 +480,5 @@
         }
 
-# endif	
+# endif
         psArrayAdd (table, 100, row);
         psFree (row);
Index: trunk/psModules/src/objects/pmSourceIO_CMF_PS1_V2.c
===================================================================
--- trunk/psModules/src/objects/pmSourceIO_CMF_PS1_V2.c	(revision 26923)
+++ trunk/psModules/src/objects/pmSourceIO_CMF_PS1_V2.c	(revision 26964)
@@ -69,9 +69,12 @@
     float magOffset = NAN;
     float exptime   = psMetadataLookupF32 (&status1, fpa->concepts, "FPA.EXPOSURE");
-    float zeropt    = psMetadataLookupF32 (&status2, imageHeader, "ZPT_OBS");
-    float zeroptErr = psMetadataLookupF32 (&status2, imageHeader, "ZPT_ERR");
+    float zeropt    = psMetadataLookupF32(&status2, fpa->concepts, "FPA.ZP");
+    if (!isfinite(zeropt)) {
+        zeropt    = psMetadataLookupF32 (&status2, imageHeader, "ZPT_OBS");
+    }
     if (status1 && status2 && (exptime > 0.0)) {
         magOffset = zeropt + 2.5*log10(exptime);
     }
+    float zeroptErr = psMetadataLookupF32 (&status2, imageHeader, "ZPT_ERR");
 
     // if the sequence is defined, write these in seq order; otherwise