Index: /branches/eam_branches/ipp-20211108/psModules/src/astrom/pmAstrometryObjects.c
===================================================================
--- /branches/eam_branches/ipp-20211108/psModules/src/astrom/pmAstrometryObjects.c	(revision 41926)
+++ /branches/eam_branches/ipp-20211108/psModules/src/astrom/pmAstrometryObjects.c	(revision 41927)
@@ -41,4 +41,5 @@
 float psVectorSystematicError (psVector *residuals, psVector *errors, float clipFraction);
 float pmAstrom2DSystematics (psVector *xPos, psVector *yPos, psVector *value);
+float pmAstromSubsetSystematics (psVector *value);
 
 #define PM_ASTROMETRYOBJECTS_DEBUG 1
Index: /branches/eam_branches/ipp-20211108/psModules/src/imcombine/pmStack.c
===================================================================
--- /branches/eam_branches/ipp-20211108/psModules/src/imcombine/pmStack.c	(revision 41926)
+++ /branches/eam_branches/ipp-20211108/psModules/src/imcombine/pmStack.c	(revision 41927)
@@ -1555,8 +1555,10 @@
     for (int i = 0; i < stackData->n; i++) {
         pmStackData *data = stackData->data[i]; // Stack data for this input
-        pmReadout *ro = data->readout;  // Readout of interest
-        stackReadouts->data[i] = psMemIncrRefCounter(ro);
-    }
-
+	stackReadouts->data[i] = NULL;
+	if (!data) continue;
+	pmReadout *ro = data->readout;  // Readout of interest
+	if (!ro) continue;
+	stackReadouts->data[i] = psMemIncrRefCounter(ro); // need to bump the counter since the free below will decrement
+    }
     if (!pmReadoutStackValidate(&minInputCols, &maxInputCols, &minInputRows, &maxInputRows, &xSize, &ySize, stackReadouts)) {
 	psError(psErrorCodeLast(), false, "Input stack is not valid.");
@@ -1590,5 +1592,7 @@
 
 		pmStackData *data = stackData->data[i]; // Stack data for this input
+		if (!data) continue;
 		pmReadout *ro = data->readout;  // Readout of interest
+		if (!ro) continue;
 
 		psAssert (ro->mask,     "must must exist, but does not");
@@ -1718,4 +1722,5 @@
     psFree(pixelVariances);
     psFree(expTime);
+
     return (true);
 }
Index: /branches/eam_branches/ipp-20211108/psModules/src/objects/pmSourceMatch.c
===================================================================
--- /branches/eam_branches/ipp-20211108/psModules/src/objects/pmSourceMatch.c	(revision 41926)
+++ /branches/eam_branches/ipp-20211108/psModules/src/objects/pmSourceMatch.c	(revision 41927)
@@ -470,4 +470,5 @@
         }
         psTrace("psModules.objects", 3, "Transparency for image %d: %f\n", i, trans->data.F32[i]);
+        psLogMsg("psModules.objects", PS_LOG_INFO, "Transparency for image %d: %f\n", i, trans->data.F32[i]);
     }
     psFree(accum);