How to specify yaw in launch file?

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Hi,

I'm having trouble getting my robot to face the right direction when it is spawned in the Gazebo world. Here's what I have in my launch file:

<node name="spawn_urdf" pkg="gazebo_ros" type="spawn_model" output="screen"
      args="-urdf -model clearpath_jackal -param robot_description -x 0 -y -10 -z 1.0 -Y 1.5708" />

Note that I'm trying to use the -Y argument to specify yaw but when I launch Gazebo the robot is always facing the same way, regardless of what value I specify.

Can anybody make any suggestions?