Index: trunk/MagicSoft/Mars/manalysis/MHillasSrc.cc
===================================================================
--- trunk/MagicSoft/Mars/manalysis/MHillasSrc.cc	(revision 1348)
+++ trunk/MagicSoft/Mars/manalysis/MHillasSrc.cc	(revision 1350)
@@ -75,5 +75,5 @@
     fHeadTail = cd*sx + sd*sy;                     // [mm]
     fDist     = sqrt(sx*sx + sy*sy);               // [mm]
-    fAlpha    = atan2(cd*sy - sd*sx, fHeadTail);   // [rad]
+    fAlpha    = atan((cd*sy - sd*sx)/fHeadTail);   // [rad]
     fAlpha   *= kRad2Deg;                          // [deg]