This is a video from GEM Systems UAV testing grounds with the GEM Systems AirBIRD and GEMCopter, from summer 2016.
The AirBIRD towed magnetometer system for UAVs weighs only 3.6 kg and contains (1) GSMP 35U high sensitivity magnetometer, complete with battery, tow cable, GPS, IMU, laser altimeter, and real-time data transfer via radio link.
To find out more about GEM Systems UAV solutions, see: http://www.gemsys.ca/uavs-pathway-to-the-future/
