The magnetometers on Vega 1 and Vega 2 were
designed to measure the magnetic field and its low-frequency fluctuations in the
cometary and solar wind interaction zone and in interplanetary space. The
instrument on each spacecraft consisted of two fluxgate sensor units (one axial
and triaxial) mounted 1 m apart on a 2-m boom. The advantage of this dual-sensor fluxgate system is the possibility to determine the spacecraft's stray magnetic field.

The axial unit was oriented along the spacecraft symmetry (X) axis, which was
perpendicular to the solar panels and pointed toward the Sun. Each sensor had a
dynamic range of ± 100 nT, sensitivity of 0.05 nT (12 bit) and a noise level of 0.01 nT/Hz^(1/2). Magnetic field vectors were measured with a sampling frequency of 10 vectors per second.

The magnetometers operated in three data rate modes:

• 1. the measured components were averaged during 2.5 minutes and transmitted to telemetry;
• 2. the measured components were averaged during 1 minute and transmitted to telemetry;
• 3. direct transmission mode, the measured components were transmitted to telemetry without averaging.

Cruise phase data were mostly taken in the 2.5-min averaging mode.