diff --git a/Utilities.js b/Utilities.js
index 1639bdb62..7325e599f 100644
--- a/Utilities.js
+++ b/Utilities.js
@@ -8,7 +8,7 @@ function getSimulationParams () {
   let timePeriod = timePeriodArray[currentTimePeriod.timePeriodIndex][1]
 
   let simulationParams = {
-    beginDatetime: dateAtScreenCorner.valueOf(),
+    beginDatetime: dateAtScreenCorner,
     timePeriod: timePeriod,
     timestamp: (new Date()).valueOf()
   }