Poleward and equatorward edge of the auroral oval modeled using the Starkov (1994) auroral boundary model as summarized in Sigernes et al. (2011). Boundaries are plotted for Kp = 8 (blue) and Kp = 9 (red) in magnetic latitude/magnetic local time coordinates. Because of the almost perfect overlap of the contours, the Kp = 8 boundary is plotted with a thicker line. Dashed lines indicate a magnetic latitude in 10° increments and magnetic local time in 2-h increments. Kp = 8 and Kp = 9 were chosen to represent moderate and severe activity, as described by the ICAO thresholds for auroral absorption, see Section 3.