3017 20170106120421.0 10.1007/s11207-016-0892-3 DOI SCART-2017-0013 Lefèvre, Laure Detailed Analysis of Solar Data Related to Historical Extreme Geomagnetic Storms: 1868 - 2010 2016 An analysis of historical Sun-Earth connection events in the context of the most extreme space weather events of the last ˜150 years is presented. To identify the key factors leading to these extreme events, a sample of the most important geomagnetic storms was selected based mainly on the well-known aa index and on geomagnetic parameters described in the accompanying paper (Vennerstrøm et al., Solar Phys. in this issue, 2016, hereafter Paper I). This part of the analysis focuses on associating and characterizing the active regions (sunspot groups) that are most likely linked to these major geomagnetic storms. STCE Historical data Extreme events Solar storms Geomagnetic storms Flares, Active regions Sunspots Statistics Vennerstrøm, Susanne Dumbović, Mateja Vršnak, Bojan Sudar, Davor Arlt, Rainer Clette, Frédéric Crosby, Norma Solar Physics 291 2016 5 1483-1531 laure.lefevre@observatoire.be published in REFERD