EG & G 811-13 proton magnetometer

The towed magnetometer has the following specifications:

Table 6: G811 Magnetometer specifications.

Noise level	90% of all readings within the selected envelope
Absolute total field	+/- 0.5 nT or less
Dynamic range	17.000 to 95.000 nT
Tuning	Fully automatic after manual selection of the ambient field
Sampling rate	From 0. to 6 secs.

During the cruise the sensor was towed at a distance of 200 m from the stern (230 m from antenna) at an average speed of 6-7 knots. The cycle measurement (sampling rate) chosen was 1 sec. thus one measurement every 3- 4 metres. The regional field in this area of NE Atlantic was around 41.000 gammas. A layback correction to the sensor position was applied by the navigation software.