Index: trunk/FACT++/src/datalogger.cc
===================================================================
--- trunk/FACT++/src/datalogger.cc	(revision 12636)
+++ trunk/FACT++/src/datalogger.cc	(revision 12637)
@@ -1262,5 +1262,5 @@
     const Time cTime(I->getTimestamp(), I->getTimestampMillisecs()*1000);
     fQuality = I->getQuality();
-    fMjD = cTime.Mjd();
+    fMjD = cTime.Mjd() ? cTime.Mjd()-40587 : 0;
 
     //figure out which run file should be used