GEM Systems GSM-19 Overhauser Magnetometer
GSM-19 Overhauser magnetometers are the choice of the ground magnetic survey industry. They are the lightest and simplest to use of any magnetometer on the market. With in-built navigation there is no need to carry a handheld GPS. Handheld GPS units can reduce the data quality because they are magnetic. They also add additional and unnecessary complexity to a ground magnetic survey. Don’t carry one! Really – you don’t have to since the GEM systems navigation works just fine.
Overhauser magnetometers have fewer external wires than all other magnetometers which means they are less likely to hook on trees. Nonetheless, when Modern Mag uses an overhauser backpack in its generic form we use metres of electrical tape to tape the GPS and sensor cables to the poles. Of course Modern Mag now uses and sells a custom backpack that virtually eliminates external cables that can hook on trees.
The really incredible thing about the Overhauser magnetometer is its power usage. The entire unit only draws 1.5 watts even with a GPS. This means that one small 2.2Ah battery lasts all day! This battery is also inside the console, which means that there are no external wires to the battery.
The GSM-19 Overhauser magnetometer has a 0.022nT sensitivity at 1Hz. This blows away proton magnetometers and approaches the sensitivity of Cesium magnetometers for much less cost. The “Overhauser mag” has absolutely no heading error and a gradient tolerance of over 3x that of a proton magnetometer.
VLF and gradiometer systems are optional add-ons. These systems are all controlled through the one console (computer).
The GEM systems GSM-19 Overhauser is the most bullet proof magnetometer commercially available. This explains why most rental companies have these units in their rental pool. They can survive and navigate thick vegetation, all the while acquiring very high quality data.
If you need a light, rugged, accurate, and easy to use magnetometer with built in navigation, then the Overhauser mag is for you. It’s also the one the pros use.
