When the Auk is equipped with an IMU accessory, It is necessary to recalibrate the
magnetometer in the IMU whenver the location or environment of the camera is significantly
changed. These values contain the calibration offsets for the X and Y magnetometer axis.
To recalibrate the camera, the camera application must be launced from a user shell, either over
the serial port or SSH. The shell must terminate the existing "aukmain" and restart it with local
control. After aukmain is running, the logging level should be set to 4 so that IMU measurements
are continously output to the terminal window, and the calibration values set to 0.
Ideally the IMU will output symmetrical values when it aligned North to South or South to North.
e.g. -400 to +400. Actually, the values will be offset: e.g. -100 to +500. The calibration value
for each axis is the offset that will make the readings symmetrical, in this case -200.