This attribute allows you to select the Coordinate System used in defining an MCS segment.
Astrogator <Satellite Object Path> SetValue <Astrogator Object Path>.CoordinateSystem {Coordinate System}
You can use any coordinate system that is defined in the Vector Geometry Tool. Make certain that the name is copied exactly and that spaces are replaced by underscores. In addition, the coordinate system name must be preceded by the class name (for example, CentralBody) and a forward slash "/". If you require additional coordinate systems, you can define them using the Vector Geometry Tool.
Astrogator */Satellite/Satellite1 SetValue MainSequence.SegmentList.Initial_State.CoordinateSystem "CentralBody/Mars Inertial"
STK Programming Interface 11.0.1