Index: trunk/Ohana/src/getstar/include/dvoImageOverlaps.h
===================================================================
--- trunk/Ohana/src/getstar/include/dvoImageOverlaps.h	(revision 41487)
+++ trunk/Ohana/src/getstar/include/dvoImageOverlaps.h	(revision 41488)
@@ -22,4 +22,6 @@
 int ACCEPT_ASTROM;
 
+double MAX_CERROR;
+
 int  args_overlaps    	 PROTO((int argc, char **argv));
 int  ConfigInit_overlaps PROTO((int *argc, char **argv));
Index: trunk/Ohana/src/getstar/src/ConfigInit_overlaps.c
===================================================================
--- trunk/Ohana/src/getstar/src/ConfigInit_overlaps.c	(revision 41487)
+++ trunk/Ohana/src/getstar/src/ConfigInit_overlaps.c	(revision 41488)
@@ -44,4 +44,7 @@
   if (*CATFORMAT == 0) strcpy (CATFORMAT, "ELIXIR");
 
+  MAX_CERROR = 0.5; // arcseconds
+  ScanConfig (config, "OVERLAPS_MAX_CERROR",     "%lf", 0, &MAX_CERROR);
+
   free (config);
   free (file);
Index: trunk/Ohana/src/getstar/src/MatchImages.c
===================================================================
--- trunk/Ohana/src/getstar/src/MatchImages.c	(revision 41487)
+++ trunk/Ohana/src/getstar/src/MatchImages.c	(revision 41488)
@@ -19,4 +19,9 @@
   if (!WITH_PHU && !strcmp (&image[0].coords.ctype[4], "-DIS")) return NULL;
   if ( SOLO_PHU &&  strcmp (&image[0].coords.ctype[4], "-DIS")) return NULL;
+
+  // exclude chips / images with errors larger than OVERLAP_MAX_CERROR:
+  if (fabs(MAX_CERROR) > 1e-6) {
+    if (image[0].cerror * 0.02 > MAX_CERROR) return NULL;
+  }
 
   /* project onto rectilinear grid with 1 arcsec pixels */
Index: trunk/Ohana/src/getstar/src/ReadImageHeader.c
===================================================================
--- trunk/Ohana/src/getstar/src/ReadImageHeader.c	(revision 41487)
+++ trunk/Ohana/src/getstar/src/ReadImageHeader.c	(revision 41488)
@@ -93,5 +93,5 @@
   }
     
-  /* CERROR in data file is in arcsec */
+  /* CERROR in data file is in arcsec, image structure uses units of 20 mas */
   if (!gfits_scan (header, "CERROR",   "%lf", 1, &tmp)) tmp = 1.0;
   image[0].cerror = tmp * 50.0;