Broadband electric field fluctuations with typical amplitudes of 10--20 mV/m peak-to-peak and frequencies from 0 Hz to 3 kHz (BB-ELF) were observed coincident with a region of ≤200 eV transverse H+ acceleration (TAI) near the poleward edge of the pre-midnight aurora. The coherence and phase velocity of the electric fields were measured using a interferometric antenna array over the frequency range of ≈100 Hz to 3 kHz. These electric field fluctuations were found to have the following characteristics: 1) incoherence perpendicular to the geomagnetic field, 2) coherence parallel to the geomagnetic field, 3) parallel phase velocity (&ohgr;/k∥) of 30--35 km/s upwards, 4) 0<|k∥/k⊥|<0.22. We show that these properties are compatible with the emission being electrostatic H+ cyclotron (EHC) waves. We also discuss possible generation mechanisms for the waves, and their relationship to the TAI. ¿ American Geophysical Union 1996