Geomagnetic indices and lists of remarkable geomagnetic events constitute data series aiming at describing at a planetary scale the magnetic activity, or some of its components. The data series are homogeneous since 1868 for aa and the list of ssc, 1932 for Kp, 1953 for the list of Sfe, 1957 for Dst and 1959 for am.
The International Service of Geomagnetic Indices (ISGI) is in charge of the elaboration and dissemination of geomagnetic indices, and of lists of remarkable magnetic events with data provided by geomagnetic observatories
ISGI collaborating institutes: ISGI/LATMOS (ex C.E.T.P.), GeoForschungsZentrum (GFZ) Potsdam Adolf-Schmidt observatorium for Geomagnetismus Observatorio del Ebro, WDC-C2 for Geomagnetism Faculty of Sciences Kyoto University, WDC for Geomagnetism Geomagnetism and Space Physics Danish Meteorological Institute (DTU World Data Center for Geomagnetism page) Arctic and Antarctic Research Institute Department of Geophysics,
The geomagnetic indices derivation, meaning and availability see: http://isgi.unistra.fr/geomagnetic_indices.php
ISGI headquarters have been moved from LATMOS (Guyancourt, France) to EOST(Strasbourg, France)