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AA Geomagnetic Activity Indices From Two Antipodal Observatories in Australia and England

Published by NOAA National Centers for Environmental Information | National Oceanic and Atmospheric Administration, Department of Commerce | Catalog Last Checked: April 12, 2026 at 04:41 AM | Dataset Last Updated: January 01, 1968 at 12:00 AM
The NOAA National Centers for Environmental Information (formerly National Geophysical Data Center) receives, on a monthly basis, indices that are based on the data from two approximately antipodal observatories in England and Australia. The AA-indices are available from 1868 to present.

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