We present analysis of electrostatic waves around the ramp a quasi-perpendicular Earth's bow shock observed by Magnetospheric Multiscale spacecraft. The have amplitudes up to 800 mV/m, which is largest value ever reported in shock. In contrast previous studies, large potential, 20 V or 20% local electron temperature. wavelengths are from 150 m 3 km, that 15 300 Debye lengths and typically 0.4 1...