Index: trunk/FACT++/scripts/CheckUnderflow.js
===================================================================
--- trunk/FACT++/scripts/CheckUnderflow.js	(revision 16077)
+++ trunk/FACT++/scripts/CheckUnderflow.js	(revision 16078)
@@ -160,5 +160,10 @@
         console.out("Trying to restore last DRS calibration #"+nn+"  ["+runs.time+"]");
 
-        var night = new Date(runs.time-1000*60*60*12);
+        var night;
+        if (Sun.horizon(null, runs.time).isUp)
+            night = new Date(runs.time);
+        else
+            night = new Date(runs.time-1000*60*60*12);
+
         var yy = night.getUTCFullYear();
         var mm = night.getUTCMonth()+1;