Index: trunk/psModules/src/objects/pmSourceSky.c
===================================================================
--- trunk/psModules/src/objects/pmSourceSky.c	(revision 34403)
+++ trunk/psModules/src/objects/pmSourceSky.c	(revision 35560)
@@ -122,8 +122,13 @@
     psTrace("psModules.objects", 10, "---- %s() begin ----\n", __func__);
     PS_ASSERT_PTR_NON_NULL(source, false);
-    PS_ASSERT_IMAGE_NON_NULL(source->variance, false);
     PS_ASSERT_IMAGE_NON_NULL(source->maskObj, false);
     PS_ASSERT_PTR_NON_NULL(source->peak, false);
     PS_ASSERT_INT_POSITIVE(Radius, false);
+
+    if (source->variance == NULL) {
+      // XXX this is needed so psphotCheckRadiusPSF has a real value
+      source->moments->dSky = 1.0;
+      return true;
+    }
 
     // maskVal is used to test for rejected pixels, and must include markVal