Cluster observation of magnetic structure and electron flows at a northward interplanetary magnetic field x-line

On March 18, 2002, the Cluster satellites traveled from the earth's northern mantle into the magnetosheath. During this time, the IMAGE spacecraft observed a long-lived proton emission northward of the auroral zone. The Cluster electron and magnetic field data suggest Cluster passed within 1 km of an active reconnection line, entering the ion diffusion region and the edge of the electron diffusion region. We present the current structure, velocity, orientation, and size of the reconnection line. The functional fit to the data also gives an estimate of 100 km for the thickness of the current sheet. We propose that the x-line, though wavering over the spacecraft, is globally stable during Cluster's passage through the magnetopause