Index: /trunk/ippconfig/gpc1/psastro.config
===================================================================
--- /trunk/ippconfig/gpc1/psastro.config	(revision 34965)
+++ /trunk/ippconfig/gpc1/psastro.config	(revision 34966)
@@ -382,4 +382,5 @@
    PSASTRO.USE.MODEL           BOOL FALSE
    PSASTRO.MOSAIC.MODE         BOOL FALSE
+   DVO.GETSTAR.FIXED.ZEROPT    F32   25.0
 
    PSASTRO.CATDIR               	STR     PS1.REF.20120524
@@ -400,4 +401,5 @@
     PSASTRO.USE.MODEL           BOOL FALSE
     PSASTRO.MOSAIC.MODE         BOOL FALSE
+    DVO.GETSTAR.FIXED.ZEROPT    F32   25.0
 
     PSASTRO.CATDIR                       STR     PS1.REF.20120524
@@ -425,4 +427,5 @@
    PSASTRO.USE.MODEL           BOOL FALSE
    PSASTRO.MOSAIC.MODE         BOOL FALSE
+   DVO.GETSTAR.FIXED.ZEROPT    F32   25.0
 
    PSASTRO.CATDIR                       STR     PS1.REF.20120524
@@ -449,4 +452,5 @@
    PSASTRO.USE.MODEL           BOOL FALSE
    PSASTRO.MOSAIC.MODE         BOOL FALSE
+   DVO.GETSTAR.FIXED.ZEROPT    F32   25.0
 
    PSASTRO.CATDIR                       STR     PS1.REF.20120524
Index: /trunk/ippconfig/recipes/psastro.config
===================================================================
--- /trunk/ippconfig/recipes/psastro.config	(revision 34965)
+++ /trunk/ippconfig/recipes/psastro.config	(revision 34966)
@@ -190,4 +190,8 @@
 DVO.GETSTAR.MIN.MAG.INST      F32     -15.0
 
+# if non-zero use as the zero point for computing magnitude limits for getstar
+# by default use the ZEROPT in the PHOTCODE.DATA
+DVO.GETSTAR.FIXED.ZEROPT      F32       0.0     
+
 ZERO.POINT.BY.EXPOSURE	      	BOOL     TRUE
 ZERO.POINT.USE.MEAN	      	BOOL     TRUE
Index: /trunk/psastro/src/psastroLoadRefstars.c
===================================================================
--- /trunk/psastro/src/psastroLoadRefstars.c	(revision 34965)
+++ /trunk/psastro/src/psastroLoadRefstars.c	(revision 34966)
@@ -363,4 +363,7 @@
     if (!status) ESCAPE ("missing DVO.GETSTAR.MIN.MAG.INST");
 
+    // if non zero override the zero point for the photcode (for stacks)
+    float fixedzeropt = psMetadataLookupF32(&status, recipe, "DVO.GETSTAR.FIXED.ZEROPT");
+
     // PHOTCODE.DATA is a multi of metadata items
     psListIterator *iter = psListIteratorAlloc(item->data.list, PS_LIST_HEAD, false);
@@ -391,4 +394,8 @@
             continue;
         }
+        if (fixedzeropt != 0.0) {
+            // override the recipe's zero point with the fixed value (for stacks)
+            zeropt = fixedzeropt;
+        }
 
         // convert the minInst to a calibrated minimum magnitude