O3/CNAF/3-registration.md

@@ -218,4 +218,18 @@ using
 An example will be provided elsewhere.
 
 ## Online registration
+Online registration, where `gwrucio_registrar` is run as a background process
+which monitors for the appearance of new frames, is almost identical to the
+offline registration procedure above and we can use exactly the same
+registration file.
+
+The only differences are:
+ 1. Remove the `--run-once` option
+ 1. Launch `gwrucio_registrar` under `nohup` and direct output to a log file.
+
+As of 1200 EST 03/05/2019, this process is running on
+`ldas-pcdev6.ligo.caltech.edu` to register h(t) from H, L and V as it arrives
+at LIGO-CIT.
+
+