This investigation used a triaxial fluxgate magnetometer (MAG-A),
similar to one on board DE 2, to obtain vector magnetic
field data needed to study the magnetosphere-ionosphere-
atmosphere coupling.

     The primary objective of this
     investigation was to obtain measurements of field-aligned
     currents in the auroral oval and over the polar cap at two
     different altitudes. This was accomplished using the two
     spacecraft and correlations of these measurements with
     observations of electric fields, plasma waves, suprathermal
     particles, thermal particles, and auroral images obtained from
     investigation 81-070A-03. Ultra low frequency (ULF) waves were
     also studied.
    
     The magnetometer incorporated its own 12-bit
     analog-to-digital converter, a 4-bit digital compensation
     register for each axis, and a system control to generate a 48-
     bit data word consisting of a 16-bit representation of the
     field measured along each of the three magnetometer axes. Track
     and hold modules were used to obtain simultaneous samples on
     all three axes. Instrument bandwidth was 25 Hz. The instrument
     dynamic range was plus or minus 6.2E4 nT, and the resolution
     was plus or minus 1.5 nT in the 6.2E4 nT region, plus or minus
     0.25 nT in the 1.E3 nT region, and plus or minus 0.02 nT in the
     80 nT region. The magnetometer's digital compensation of the
     ambient field was nominally in 8.E3 nT increments.
    
     Further
     details are in W. H. Farthing et al., Space Sci. Instrum., v.
     5, n. 4, p. 551, 1981.