In panel (a) is described, from up to down, Solar flux F10.7 from 12 to 19 December 1987, and, for the same time period, the behaviour of the magnitude and the Z component of the IMF. Panel (b) shows, from up to down, the AE, the a _p and the Dst indices, from 12 to 19 December 1987. (The hourly AE index data are retrieved through the Kyoto AE index service http://wdc.kugi.kyoto-u.ac.jp/dstae/index.html. Three-hour a _p data are provided by NOAA ftp://ftp.ngdc.noaa.gov/STP/GEOMAGNETIC_DATA/INDICES/KP_AP. Dst and Solar data are obtained from NASA Goddard Space Physics Data Facilities OMNIWEB: https://omniweb.gsfc.nasa.gov/form/dx1.html).