Make sure HillasReconstructor az is in [0, 360)

ctapipe/reco/hillas_reconstructor.py

@@ -28,8 +28,6 @@
     TooFewTelescopesException,
 )
 
-
-
 __all__ = ["HillasReconstructor"]
 
 
@@ -39,6 +37,9 @@
 )
 
 
+_two_pi = 2 * np.pi
+
+
 def angle(v1, v2):
     """computes the angle between two vectors
         assuming cartesian coordinates
@@ -188,9 +189,12 @@ def __call__(self, event):
         # estimate max height of shower
         h_max = self.estimate_h_max(cog_cartesian, telescope_positions)
 
+        # az is clockwise, lon counter-clockwise, make sure it stays in [0, 2pi)
+        az = u.Quantity(_two_pi - lon.to_value(u.rad), u.rad)
+
         event.dl2.stereo.geometry[self.__class__.__name__] = ReconstructedGeometryContainer(
             alt=lat,
-            az=-lon,  # az is clockwise, lon counter-clockwise
+            az=az,
             core_x=core_pos_ground.x,
             core_y=core_pos_ground.y,
             core_tilted_x=core_pos_tilted.x,