The U.S. Air Force (USAF) issues Hourly and 24-Hour (daily) reports containing geomagnetic A and K indices and maximum gamma deflections. The Space Weather Prediction Center makes these reports available on the internet via FTP and the World Wide Web.
These are reports containing geomagnetic A and K indices and maxiumum gamma deflections.
The Space Weather Prediction Center makes these reports available; SWPC updates the files as they are received, usually between 20 and 30 minutes past the hour, and details about the product are available here.
Additional details about this product are available.
SWPC maintains a limited archive of USAF magnetometer reports. (Hourly reports are available from the last 48 hours. Daily reports are available for the last seven days.)