The GOES 2 and GOES 3 satellite high resolution magnetometer data are examined for the March 22, 1979, substorm interval selected by the Coordinated Data Analysis Workshop 6 analysis. Both GOES satellites were on the geographic equator with GOES 2 at 104¿ west geographic longitude and GOES 3 at 135¿ west geographic longitude. From the comparison of the two GOES magnetometer data sets, the spatial and temporal characteristics of the substorm-associated variations in the geomagnetic field near synchronous orbit are studied. The onset of the first substorm (expansion phase) was observed at GOES 3 at 1053 UT, and GOES 2 at 1110 UT about 17 min later. At this time, GOES 3 was at 0200 LT and GOES 3 was at 0400 LT. Prior to the expansion phase, both GOES satellites detected a growth phase during which the field was distended tailward, and the azimuthal component underwent a negative (westward) excursion. The growth phase began almost simultaneously at the two satellites. During the second substorm, the two satellites did not observe clear substorm signatures because they were at dawn. The magnetic field observations for the first substorm are characterized by the current wedge model proposed by McPherron et al. (1973).