Index: /trunk/Mars/msim/MPhotonData.cc
===================================================================
--- /trunk/Mars/msim/MPhotonData.cc	(revision 18448)
+++ /trunk/Mars/msim/MPhotonData.cc	(revision 18449)
@@ -63,5 +63,5 @@
     : fPosX(0), fPosY(0), fCosU(0), fCosV(0), fTime(0), fWavelength(0),
     /*fNumPhotons(1),*/ fProductionHeight(0), fPrimary(MMcEvtBasic::kUNDEFINED),
-    fTag(-1), fWeight(1)
+      fTag(-1), fWeight(1), fMirrorTag(-1)
 {
    // fName  = name  ? name  : "MPhotonData";
Index: /trunk/Mars/msim/MPhotonData.h
===================================================================
--- /trunk/Mars/msim/MPhotonData.h	(revision 18448)
+++ /trunk/Mars/msim/MPhotonData.h	(revision 18449)
@@ -43,4 +43,5 @@
 
     Int_t   fTag;    //! A tag for external use
+    Int_t   fMirrorTag;    // Tag for the mirror ID of the mirror which was hit by this photon
     Float_t fWeight; //! A weight for external use
 
@@ -108,4 +109,7 @@
     Int_t GetTag() const { return fTag; }
 
+    void SetMirrorTag(Int_t mirrorTag) { fMirrorTag=mirrorTag; }
+    Int_t GetMirrorTag() const { return fMirrorTag; }
+
     // TObject
     //void Clear(Option_t * = NULL);
Index: /trunk/Mars/msimreflector/MSimReflector.cc
===================================================================
--- /trunk/Mars/msimreflector/MSimReflector.cc	(revision 18448)
+++ /trunk/Mars/msimreflector/MSimReflector.cc	(revision 18449)
@@ -532,4 +532,8 @@
         dat->SetDirection(w);
 
+        // FTemme: As dat.fTag is later changed from mirror ID to pixel ID, here
+        // also dat.fMirrorTag is set to num:
+        dat->SetMirrorTag(num);
+
         (*fMirror3)[cnt[3]++] = *dat;
         //*static_cast<MPhotonData*>(cpy3.UncheckedAt(cnt[3]++)) = *dat;