diff --git a/ObservationSim/_util.py b/ObservationSim/_util.py
index 87cfcc3fb5810be4cdb769a479a1dcc2c3e05284..d8b57134e903c382ed34c8d96b96e6f9d12629f6 100755
--- a/ObservationSim/_util.py
+++ b/ObservationSim/_util.py
@@ -43,6 +43,10 @@ def generate_pointing_list(config, pointing_filename=None, data_dir=None):
         ipoint += 1
 
     run_pointings = config['obs_setting']['run_pointings']
+    if config["obs_setting"]["exp_time"]:
+        exp_time = config["obs_setting"]["exp_time"]
+    else:
+        exp_time = 150.
     
     if pointing_filename and data_dir:
         pointing_file = os.path.join(data_dir, pointing_filename)
@@ -57,7 +61,7 @@ def generate_pointing_list(config, pointing_filename=None, data_dir=None):
                 continue
             line = line.strip()
             columns = line.split()
-            pointing = Pointing()
+            pointing = Pointing(exp_time=exp_time)
             pointing.read_pointing_columns(columns=columns, id=ipoint, t=t)
             t += delta_t * 60.
             pointing_list.append(pointing)
@@ -71,6 +75,7 @@ def generate_pointing_list(config, pointing_filename=None, data_dir=None):
             dec=config["obs_setting"]["dec_center"],
             img_pa=config["obs_setting"]["image_rot"],
             timestamp=t,
+            exp_time=exp_time,
             pointing_type='MS'
             )
         t += delta_t * 60.