Helicopter Detecting

[Zig-Zag]

I was camping at an old mine last month and a helicopter flew around slowly only 20 feet off the ground. It had a long pole off the front with a large red sensor of some sort. What kind of long-range detector might they have been using?

 

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[chlsbrns]

It might be a magnetometer

https://www.google.com/search?q=hel...n.2,or.r_qf.&cad=b&sei=DEjEUaihD7TI4AOfs4HwBw


Magnetometer « Stratus Aeronautics