Index: trunk/Ohana/src/opihi/cmd.astro/star.c
===================================================================
--- trunk/Ohana/src/opihi/cmd.astro/star.c	(revision 7917)
+++ trunk/Ohana/src/opihi/cmd.astro/star.c	(revision 26891)
@@ -24,4 +24,5 @@
   if ((argc != 4) && (argc != 5)) {
     gprint (GP_ERR, "USAGE: star (buffer) x y [dx] [-border N] [-sat cnts]\n");
+    gprint (GP_ERR, " dx is the aperture diameter, but is adjusted up to the next odd number\n");
     return (FALSE);
   }