Kind of a noob localization question. I have a Phidgets imu that publishes magnetic field data (/imu/mag, type sensor_msgs/MagneticField) as well as odom data (/imu/data, type sensor_msgs/Imu). Does anybody know if the Phidgets imu is internally using the magnetic field data as part of updating /imu/data? Or should that be done externally?