diff --git a/ObservationSim/MockObject/SpecDisperser/SpecDisperser.py b/ObservationSim/MockObject/SpecDisperser/SpecDisperser.py
index 9a6a64df6aeceb439d97764cbc66516b9734f55b..a9ae5de8d02d638320bb98655086937382eaa120 100644
--- a/ObservationSim/MockObject/SpecDisperser/SpecDisperser.py
+++ b/ObservationSim/MockObject/SpecDisperser/SpecDisperser.py
@@ -194,13 +194,13 @@ class SpecDisperser(object):
         originOut_x = origin_in[1] + dx0_in - 1
         originOut_y = origin_in[0] + dy0_in - 1
 
-        return model, originOut_x, originOut_y
+        return model, originOut_x, originOut_y, dxpix, dypix, lam_beam[lam_index],ysens[lam_index]
 
-    def writerSensitivityFile(self, conffile = '', beam = '', w = None, sens = None):
-        orders={'A':'1st','B':'0st','C':'2st','D':'-1st','E':'-2st'}        
-        sens_file_name = conffile[0:-5]+'_sensitivity_'+ orders[beam] + '.fits'
+    def writerSensitivityFile(self, conffile='', beam='', w=None, sens=None):
+        orders = {'A': '1st', 'B': '0st', 'C': '2st', 'D': '-1st', 'E': '-2st'}
+        sens_file_name = conffile[0:-6] + '.sensitivity.' + orders[beam] + '.fits'
         if not os.path.exists(sens_file_name) == True:
-            senstivity_out = Table(array([w,sens]).T, names=('WAVELENGTH', 'SENSITIVITY'))
+            senstivity_out = Table(array([w, sens]).T, names=('WAVELENGTH', 'SENSITIVITY'))
             senstivity_out.write(sens_file_name, format='fits')