An example showing the ACE solar wind data and Kp. The top two panels show the IMF B_z (GSM) and B 1-minute averages (blue curve), 3-hour averages (dashed line segments), and 3-hour minima and maxima (solid line segments). The middle panel shows the solar wind speed. The fourth panel shows final Kp. The solid blue line segments show the Kp values over their 3-hour intervals. Each dot shows the Kp value at the end of the 3-hour interval, with linearly interpolated values connecting the dots (dashed lines). The red horizontal lines show nowcast Kp determined from geomagnetic data up to 22:50UT and up to 23:00UT, respectively. The bottom panel shows the horizontal geomagnetic field at NGK with 1-minute resolution. The ACE 1-minute averages are the propagated values from L1 to Earth using the solar wind speed. The timestamp at the top indicates the location of the vertical dotted line.