Index: /branches/eam_branches/ipp-20230313/ppStack/src/ppStackConvolve.c
===================================================================
--- /branches/eam_branches/ipp-20230313/ppStack/src/ppStackConvolve.c	(revision 42563)
+++ /branches/eam_branches/ipp-20230313/ppStack/src/ppStackConvolve.c	(revision 42564)
@@ -203,5 +203,6 @@
         }
         psFree(maskHeader);
-        if (!ppStackWriteVariance(options->convVariances->data[i], hdu->header, readout->variance, readout->covariance->image, config)) {
+	psImage *covarImage = readout->covariance ? readout->covariance->image : NULL;
+        if (!ppStackWriteVariance(options->convVariances->data[i], hdu->header, readout->variance, covarImage, config)) {
             psError(PPSTACK_ERR_IO, false, "Unable to write convolved variance %d", i);
             psFree(fpaList);
@@ -216,8 +217,10 @@
         {
             psString name = NULL;
-            psStringAppend(&name, "covariance_%d.fits", i);
-            ppStackWriteImage(name, hdu->header, readout->covariance->image, config);
-            pmStackVisualPlotTestImage(readout->covariance->image, name);
-            psFree(name);
+	    if (readout->covariance) {
+	      psStringAppend(&name, "covariance_%d.fits", i);
+	      ppStackWriteImage(name, hdu->header, readout->covariance->image, config);
+	      pmStackVisualPlotTestImage(readout->covariance->image, name);
+	      psFree(name);
+	    }
         }
         {