diff --git a/simulations/airshower_beacon_simulation/lib/rit.py b/simulations/airshower_beacon_simulation/lib/rit.py
index 024dcb6..db2704c 100644
--- a/simulations/airshower_beacon_simulation/lib/rit.py
+++ b/simulations/airshower_beacon_simulation/lib/rit.py
@@ -93,10 +93,9 @@ def shower_plane_slice(e,X=750.,Nx=10,Ny=10,wx=1e3,wy=1e3,xoff=0,yoff=0,zgr=0,n_
 
     def loop_func(x_, y_, xoff=xoff, yoff=yoff):
             loc = (x_+xoff)* e.uAxB + (y_+yoff)*e.uAxAxB + dX *e.uA
-            locs.append(loc)
             P,t_,pulses_,wav,twav = pow_and_time(loc,e)
 
-            return x_+xoff, y_+yoff, P, locs
+            return x_+xoff, y_+yoff, P, loc
 
     res = ( delayed(loop_func)(x_, y_) for x_ in x for y_ in y)
 
@@ -107,6 +106,10 @@ def shower_plane_slice(e,X=750.,Nx=10,Ny=10,wx=1e3,wy=1e3,xoff=0,yoff=0,zgr=0,n_
     # unpack loop results
     xx, yy, p, locs = zip(*res)
 
+    xx = np.asarray(xx)
+    yy = np.asarray(yy)
+    p = np.asanyarray(p)
+
     return xx,yy,p,locs[np.argmax(p)]
 
 def slice_figure(e,X,xx,yy,p,mode='horizontal'):