Unsettled geomagnetic conditions continued this week, punctuated by periods of relative quiet. The most active days were July 14-15. The planetary A index was 20 and 25, and the mid-latitude A index was 15 and 33 on those dates. Of course Alaska’s College A index was higher, at 58 and 34.
The A index is a daily value, and it is calculated from eight measurements per day (once every three hours) …
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