diff --git a/ObservationSim/ObservationSim.py b/ObservationSim/ObservationSim.py
index 278b56023cc935e831cc28e470301675eb53ae2b..891d4cd56c40561e9d4d1559aebde6f97a1a52ca 100755
--- a/ObservationSim/ObservationSim.py
+++ b/ObservationSim/ObservationSim.py
@@ -99,6 +99,9 @@ class Observation(object):
         sim_steps = SimSteps(overall_config=self.config, chip_output=chip_output, all_filters=self.all_filters)
 
         for step in pointing.obs_param["call_sequence"]:
+            if self.config["run_option"]["out_cat_only"]:
+                if step != "scie_obs":
+                    continue
             chip_output.Log_info("Starting simulation step: %s, calling function: %s"%(step, SIM_STEP_TYPES[step]))
             obs_param = pointing.obs_param["call_sequence"][step]
             step_name = SIM_STEP_TYPES[step]