diff --git a/ObservationSim/sim_steps/add_LED_flat.py b/ObservationSim/sim_steps/add_LED_flat.py
index 751485d79cde657158e53c1dea3f580850b3b1d2..c1123ee570f7af6fa9fa6326ff04cc378bd3c68f 100644
--- a/ObservationSim/sim_steps/add_LED_flat.py
+++ b/ObservationSim/sim_steps/add_LED_flat.py
@@ -29,7 +29,7 @@ def add_LED_Flat(self, chip, filt, tel, pointing, catalog, obs_param):
         pf_map = np.array(pf_map, dtype='float32')
         self.updateHeaderInfo(header_flag='ext', keys = ['SHTSTAT'], values = [True])
     else:
-        self.updateHeaderInfo(header_flag='ext', keys = ['SHTSTAT','SHTOPEN0','SHTOPEN1','SHTCLOS0','SHTCLOS1'], values = [False,'','','',''])
+        self.updateHeaderInfo(header_flag='ext', keys = ['SHTSTAT','SHTOPEN0','SHTOPEN1','SHTCLOS0','SHTCLOS1'], values = [True,'','','',''])
 
     chip.img = chip.img + pf_map
 
diff --git a/ObservationSim/sim_steps/add_objects.py b/ObservationSim/sim_steps/add_objects.py
index 866d5389a82f9ebd7a4905e46316ce7f84dd13ec..26f61fef3058899bfac68b5670ff5a36535777fe 100644
--- a/ObservationSim/sim_steps/add_objects.py
+++ b/ObservationSim/sim_steps/add_objects.py
@@ -211,7 +211,7 @@ def add_objects(self, chip, filt, tel, pointing, catalog, obs_param):
         flat_normal = np.array(flat_normal, dtype='float32')
         self.updateHeaderInfo(header_flag='ext', keys = ['SHTSTAT'], values = [True])
     else:
-        self.updateHeaderInfo(header_flag='ext', keys = ['SHTSTAT','SHTOPEN0','SHTOPEN1','SHTCLOS0','SHTCLOS1'], values = [False,'','','',''])
+        self.updateHeaderInfo(header_flag='ext', keys = ['SHTSTAT','SHTOPEN0','SHTOPEN1','SHTCLOS0','SHTCLOS1'], values = [True,'','','',''])
     chip.img *= flat_normal
     del flat_normal
 
diff --git a/ObservationSim/sim_steps/add_sky_background.py b/ObservationSim/sim_steps/add_sky_background.py
index 50a1731e8497e66e9503657a087d4b9f87c02610..b31f61eddf6b1f641bd616d97fd7921941f3a389 100644
--- a/ObservationSim/sim_steps/add_sky_background.py
+++ b/ObservationSim/sim_steps/add_sky_background.py
@@ -84,7 +84,7 @@ def add_sky_flat_calibration(self, chip, filt, tel, pointing, catalog, obs_param
             shutt_gsimg.write("%s/ShutterEffect_%s_1.fits" % (self.chip_output.subdir, str(chip.chipID).rjust(2, '0')))
         self.updateHeaderInfo(header_flag='ext', keys = ['SHTSTAT'], values = [True])
     else:
-        self.updateHeaderInfo(header_flag='ext', keys = ['SHTSTAT','SHTOPEN0','SHTOPEN1','SHTCLOS0','SHTCLOS1'], values = [False,'','','',''])
+        self.updateHeaderInfo(header_flag='ext', keys = ['SHTSTAT','SHTOPEN0','SHTOPEN1','SHTCLOS0','SHTCLOS1'], values = [True,'','','',''])
     
 
     if chip.survey_type == "photometric":