Data plots from the FGM instrument. Sharp decreases of the magnetic field on SC2 (red line) indicate crossing of the bow shock. The bow shock was first hovering very close to spacecraft 2 (06:50 to 07:03), then moved sunward of all four spacecraft (07:03 to 07:12). Later it stayed between spacecraft 2 and the other three spacecraft. Data courtesy of FGM Principal Investigator, Prof. Andre Balogh (Imperial College, London, UK)