diff --git a/examples/csbkgmodel.py b/examples/csbkgmodel.py
index c8f0acd..d4093e4 100644
--- a/examples/csbkgmodel.py
+++ b/examples/csbkgmodel.py
@@ -49,12 +49,17 @@ class csbkgmodel(ctools.cscript):
         self.name    = "csbkgmodel"
         self.version = "1.1.0"
 
-        # Initialise some members
-        self.obs = None
-
         # Make sure that parfile exists
         file = self.parfile()
 
+        # Initialise some members
+        if len(argv) > 0 and isinstance(argv[0],gammalib.GObservations):
+            self.obs = argv[0]
+            argv     = argv[1:]
+        else:      
+            self.obs = gammalib.GObservations()
+            self.obs.clear()  
+
         # Initialise application
         if len(argv) == 0:
             ctools.cscript.__init__(self, self.name, self.version)
@@ -122,7 +127,7 @@ class csbkgmodel(ctools.cscript):
         """
         Get parameters from parfile and setup the observation.
         """
-        if self.obs == None or self.obs.size() == 0:
+        if self.obs.size() == 0:
             self.obs = self.get_observations(False)
         
         # Read excluded regions, set flag if excluded regions are available