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Table 1.
The months of start and end, as well as the values of minimum and maximum solar activity expressed in terms of F 10.7, are shown for each of the solar cycles 21, 22 and 23. The solar cycle 24, which is not practically considered in this study, is included for completeness.
| Solar cycle | Initial month–final month | Minimum F 10.7–maximum F 10.7 (10−22 Wm−2 Hz−1) |
|---|---|---|
| 21 | June 1976–September 1986 | 72.7–207.5 |
| 22 | September 1986–May 1996 | 72.8–201.4 |
| 23 | May 1996–December 2008 | 69.6–164.7 |
| 24 | December 2008– | 64.9– |
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