Index: trunk/FACT++/src/FitsFile.cc
===================================================================
--- trunk/FACT++/src/FitsFile.cc	(revision 12605)
+++ trunk/FACT++/src/FitsFile.cc	(revision 12611)
@@ -41,5 +41,7 @@
         WriteKey("DATE",     now.Iso(), "File creation date");
         WriteKey("NIGHT",    now.NightAsInt(), "Night as int");
-        WriteKey("TIMESYS",  "UTC", "Time systen");
+        WriteKey("TIMESYS",  "UTC", "Time system");
+        WriteKey("TIMEUNIT", "d",   "Time given in days w.r.t. to MJDREF");
+        WriteKey("MJDREF",   40587, "Store times in UNIX time (for convenience, seconds since 1970/1/1)");
 
         //WriteKey("CONTACT",   PACKAGE_BUGREPORT, "Current package maintainer");