Rocket observations (AT2)

The Auroral Turbulence 2 (AT2) rocked was launched on February 11, 1997 from Poker Flat, Alaska. The rocket had three separated payloads (Main, North and East). Each payload was carrying a fluxgate magnetometer, a double probe electric field instrument and a particle detector. The AT2 reached an apogee of about 500 km. Just before apogee, AT2 crossed an intense auroral arc with a small relative velocity of 0.3 km/sec transverse to the arc.

An electron acceleration event similar to the one described in the previous section was observed by AT2 at the edge of the arc (see Figure 1 in [14,15]). Payloads separated by 3 km observe an Alfvénic activity at 0.5 Hz with electric and magnetic field oscillations almost in phase. On the other hand the detection of the envelope of these oscillations was clearly shifted in time between the payloads. This means the payloads were crossing a spatially localized region of temporal oscillations. The estimated width of the region was about 4 km which is much larger than the electron inertial length $\lambda_e \approx 160$ m. Field aligned dispersive electron precipitations were observed simultaneously on all payloads and appear to be in phase with Alfvénic fluctuations.