This experiment (E3) consisted of a boom-mounted triaxial-fluxgate magnetometer. An automatic inflight range switch system selected the optimum of four ranges: minus to plus 16, 48, 144, and 432 nT per sensor. These had corresponding digitization resolutions of minus to plus 0.03, 0.09, 0.28, and 0.84 nT. A sensor flipper was actuated every 36 h to assist in sensor zero level determination. For telemetry bit rates above 256 bps, vector measurements were made at rates between 1 and 16 per s, depending on bit rates. At lower bit rates, averages and variances were computed on board for transmission to earth. For further details, see pp. 237-240 of Raumfahrtforschung, v. 19, n. 5, 1975.