diff --git a/observation_sim/instruments/chip/effects.py b/observation_sim/instruments/chip/effects.py
index 7a6b7a667c15e5ff8bf5d740e63476cd597531d0..21735ede4ef8e5307fc645d75c4592b9e0c0e2d5 100644
--- a/observation_sim/instruments/chip/effects.py
+++ b/observation_sim/instruments/chip/effects.py
@@ -793,7 +793,7 @@ def ShutterEffectArr(GSImage, t_exp=150, t_shutter=1.3, dist_bearing=735, dt=1E-
     sizey = ymax-ymin+1
     xnewgrid = np.mgrid[xmin:(xmin+sizex)]
     expeffect = interpolate.splev(xnewgrid, intp, der=0)
-    expeffect /= np.max(expeffect)
+    expeffect /= t_exp
     exparrnormal = np.tile(expeffect, (sizey,1))
     # GSImage *= exparrnormal