Interplanetary and geomagnetic data for C05 event (21 January 2005). Interplanetary magnetic field (same panel distribution as four top panels of Fig. 5) and solar wind parameters, Vsw, N, T, in the next three panels, measured at ACE location. Eighth panel shows the dynamic pressure P_dyn. Geomagnetic data (SYM-H index and BSL observatory) are shown in bottom panel. Two different time-lines in horizontal axis have been set: top labels correspond to ACE data (eight top panels) and bottom labels correspond to ground data (bottom panel). Interplanetary plots are shifted 25 min (see text for details) relative to ground plots.Vertical solid lines, S1 and S2, mark shock discontinuities and vertical dashed lines T1 and T2 mark southward turnings of B_z.