diff --git a/operating/cacao.rst b/operating/cacao.rst
index 02b285d..7a9e91c 100644
--- a/operating/cacao.rst
+++ b/operating/cacao.rst
@@ -141,4 +141,12 @@ from either camera.
 
       [xsup@icc ncpc-rootdir]$ cacao-calib-apply llowfsTT
 
+4. To record the current star location (or rather its average) you need to take a reference with:
+
+    ::
+       [xsup@icc ncpc-rootdir]$ cacao-aorun-026-takeref -n 20000
+
+    You can change the number of measurements averaged to suit based on the exposure time of the camera in use.  This
+    sets the convergence
+