Auroral electrojet magnetic activity indices AE (11-12) for January - June 1975

The Auroral Electrojet index (AE) is discussed and a brief description is given of the derivation of 11-12 station 1.0-min AE indices for January-June 1975. Tables are given of hourly average indices for each day, of the stations making the main contribution to the hourly indices, and of the average monthly quiet-time level of horizontal fields (H) at each magnetic observatory. Graphs of the index variations are included for each day of the first half of 1975 and for the frequency and amplitude of extreme variations at each site.