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Table 1
Solar cycles 17–24, reversals of GMF of the Sun and occurrence rate of GLEs.
| Cycle | Start | Maximum | End | Reversal | GLE number per cycle | Comments |
|---|---|---|---|---|---|---|
| 17 | Sep 1933 | Apr 1937 | Feb 1944 | ?? | 2 (+8)? | IC only: Omitted GLEs? |
| 18 | Feb 1944 | May 1947 | Apr 1954 | ?? | 2 (+8)? | Second max 1948–1949? Omitted GLEs? |
| 19 | Apr 1954 | Mar 1958 | Oct 1964 | 1957–1958 | 10 | NM of IGY type |
| 20 | Oct 1964 | Nov 1968 | Jun 1976 | 1969–1972 | 13 | NM64. Weak cycle |
| 21 | Jun 1976 | Dec 1979 | Sep 1986 | 1980–1981 | 12 | NM64. Second SA max 1981 |
| 22 | Sep 1986 | Jul 1989 | May 1996 | 1991–1992 | 15 | NM64. Second SA max 1991 |
| 23 | May 1996 | Mar 2000 | Dec 2008 | 1999–2001 | 16 | NM64. Delayed SA min |
| 24 | Jan 2009 | Apr 2014 | ≥2020, Hathaway | Dec 2012 | 2 GLEs | NM64. Predicted: Weak/Slack Cycle |
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