Statistics of sunspot activity
April, 1999
Visual indices of solar activity by National Geophysical Data Center
| Date | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | Average | % |
| W | 53.00 | 54.67 | 68.00 | 89.75 | 109.50 | 122.25 | 122.67 | 126.25 | 135.00 | 118.00 | 103.67 | 110.25 | 107.67 | | | 78.00 | 91.00 | 83.00 | 69.50 | 72.75 | 61.50 | 56.67 | 70.00 | 68.25 | 65.00 | 69.00 | | 76.67 | 110.00 | 118.50 | 89.28 | 100 |
| Wn | 27.75 | 22.33 | 31.75 | 42.25 | 52.50 | 45.00 | 58.67 | 69.25 | 67.00 | 60.75 | 49.00 | 31.00 | 22.33 | | | 7.00 | 18.00 | 21.25 | 32.50 | 33.25 | 19.00 | 16.67 | 24.67 | 34.25 | 49.67 | 56.75 | | 65.67 | 104.50 | 118.50 | 43.75 | 49.00 |
| Ws | 25.25 | 32.33 | 36.25 | 47.50 | 57.00 | 77.25 | 64.00 | 57.00 | 68.00 | 57.25 | 54.67 | 79.25 | 85.33 | | | 71.00 | 73.00 | 61.75 | 37.00 | 39.50 | 42.50 | 40.00 | 45.33 | 34.00 | 15.33 | 12.25 | | 11.00 | 5.50 | 0.00 | 45.53 | 51.00 |
| n | 4.50 | 4.33 | 4.50 | 5.00 | 5.00 | 6.25 | 6.33 | 6.25 | 7.67 | 5.25 | 5.00 | 6.00 | 6.33 | | | 5.50 | 6.50 | 6.00 | 4.50 | 4.50 | 3.75 | 3.00 | 4.00 | 4.75 | 4.00 | 4.00 | | 4.00 | 7.00 | 6.25 | 5.19 | 100 |
| A | 0.50 | 1.00 | 0.25 | 0.75 | 1.00 | 0.50 | 0.67 | 1.50 | 0.67 | 0.00 | 0.00 | 0.50 | 0.67 | | | 2.00 | 1.00 | 1.50 | 0.25 | 0.75 | 0.50 | 0.00 | 1.00 | 1.25 | 0.00 | 0.00 | | 0.00 | 1.00 | 1.50 | 0.69 | 13.38 |
| B | 0.25 | 0.33 | 1.25 | 1.00 | 0.00 | 1.00 | 1.33 | 0.50 | 2.00 | 0.50 | 0.67 | 1.25 | 1.33 | | | 1.00 | 1.00 | 2.00 | 0.50 | 0.75 | 0.50 | 0.00 | 0.00 | 1.50 | 1.00 | 0.50 | | 0.33 | 1.00 | 0.25 | 0.81 | 15.52 |
| C | 0.50 | 1.00 | 0.25 | 1.00 | 1.00 | 1.25 | 0.00 | 0.75 | 0.67 | 0.25 | 0.67 | 1.75 | 2.67 | | | 1.50 | 1.50 | 0.75 | 1.75 | 1.00 | 1.00 | 1.67 | 2.00 | 1.25 | 0.33 | 0.75 | | 1.00 | 1.75 | 1.75 | 1.10 | 21.22 |
| D | 0.00 | 0.00 | 1.75 | 2.00 | 2.00 | 1.50 | 2.67 | 2.50 | 4.00 | 3.75 | 2.67 | 2.00 | 1.33 | | | 1.00 | 1.00 | 0.50 | 1.50 | 1.75 | 0.75 | 0.67 | 1.00 | 0.50 | 2.33 | 2.00 | | 0.67 | 0.25 | 0.25 | 1.49 | 28.78 |
| E | 0.00 | 0.00 | 0.00 | 0.00 | 0.50 | 0.00 | 0.33 | 0.00 | 0.00 | 0.50 | 0.67 | 0.25 | 0.00 | | | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | | 0.00 | 0.50 | 1.00 | 0.14 | 2.68 |
| F | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.25 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | | | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | | 0.00 | 0.00 | 0.50 | 0.03 | 0.54 |
| G | 0.00 | 0.00 | 0.00 | 0.00 | 0.50 | 1.75 | 1.00 | 0.50 | 0.00 | 0.00 | 0.33 | 0.25 | 0.00 | | | 0.00 | 0.50 | 0.25 | 0.00 | 0.25 | 0.00 | 0.33 | 0.00 | 0.00 | 0.00 | 0.00 | | 1.00 | 0.50 | 0.50 | 0.28 | 5.47 |
| H | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | | | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 |
| I | 3.25 | 2.00 | 1.00 | 0.25 | 0.00 | 0.25 | 0.33 | 0.25 | 0.33 | 0.25 | 0.00 | 0.00 | 0.33 | | | 0.00 | 1.50 | 1.00 | 0.50 | 0.00 | 1.00 | 0.33 | 0.00 | 0.25 | 0.33 | 0.75 | | 1.00 | 2.00 | 0.50 | 0.65 | 12.43 |
| x | 0.75 | 1.33 | 1.50 | 1.75 | 1.00 | 1.50 | 2.00 | 2.00 | 2.67 | 0.50 | 0.67 | 1.75 | 2.00 | | | 3.00 | 2.00 | 3.50 | 0.75 | 1.50 | 1.00 | 0.00 | 1.00 | 2.75 | 1.00 | 0.50 | | 0.33 | 2.00 | 1.75 | 1.50 | 28.89 |
| r | 0.25 | 0.00 | 0.25 | 0.00 | 0.00 | 0.00 | 0.33 | 0.25 | 0.00 | 0.25 | 0.33 | 0.50 | 0.00 | | | 0.00 | 0.50 | 0.25 | 0.50 | 0.00 | 0.00 | 0.00 | 0.67 | 0.25 | 0.00 | 0.25 | | 0.33 | 0.25 | 0.75 | 0.22 | 4.22 |
| s | 3.00 | 2.33 | 2.50 | 1.50 | 1.00 | 2.00 | 0.33 | 1.00 | 1.67 | 1.25 | 1.67 | 2.50 | 2.67 | | | 0.50 | 1.50 | 1.50 | 2.00 | 2.25 | 1.25 | 1.67 | 0.33 | 0.25 | 2.33 | 1.50 | | 1.33 | 3.25 | 1.75 | 1.66 | 31.99 |
| a | 0.50 | 0.67 | 0.25 | 1.75 | 3.00 | 2.75 | 3.67 | 2.50 | 3.33 | 3.25 | 2.33 | 1.25 | 1.67 | | | 2.00 | 2.50 | 0.75 | 1.25 | 0.75 | 1.50 | 1.33 | 2.00 | 1.50 | 0.67 | 1.75 | | 1.00 | 1.00 | 1.75 | 1.73 | 33.29 |
| h | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.25 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | | | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | | 0.33 | 0.00 | 0.00 | 0.02 | 0.42 |
| k | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.25 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | | | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | | 0.67 | 0.50 | 0.25 | 0.06 | 1.19 |
| x | 3.75 | 3.00 | 1.25 | 1.00 | 1.00 | 0.75 | 1.00 | 1.75 | 1.00 | 0.25 | 0.00 | 0.50 | 1.00 | | | 2.00 | 2.50 | 2.50 | 0.75 | 0.75 | 1.50 | 0.33 | 1.00 | 1.50 | 0.33 | 0.75 | | 1.00 | 3.00 | 2.00 | 1.34 | 25.80 |
| o | 0.75 | 1.33 | 3.25 | 3.75 | 2.50 | 5.50 | 4.33 | 3.75 | 5.67 | 4.00 | 4.33 | 5.00 | 5.33 | | | 3.50 | 4.00 | 3.50 | 3.75 | 3.25 | 2.00 | 2.67 | 3.00 | 3.25 | 3.67 | 3.00 | | 3.00 | 3.50 | 2.75 | 3.49 | 67.30 |
| i | 0.00 | 0.00 | 0.00 | 0.25 | 1.50 | 0.00 | 1.00 | 0.75 | 0.67 | 0.75 | 0.67 | 0.50 | 0.00 | | | 0.00 | 0.00 | 0.00 | 0.00 | 0.50 | 0.25 | 0.00 | 0.00 | 0.00 | 0.00 | 0.25 | | 0.00 | 0.50 | 1.50 | 0.34 | 6.48 |
| c | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.33 | 0.25 | 0.00 | 0.00 | 0.00 | | | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | | 0.00 | 0.00 | 0.00 | 0.02 | 0.42 |
| CV | 36.00 | 30.67 | 57.00 | 58.00 | 76.50 | 86.75 | 87.00 | 96.25 | 104.33 | 96.50 | 88.33 | 75.00 | 60.33 | | | 36.50 | 59.00 | 36.75 | 55.50 | 60.50 | 36.00 | 40.00 | 35.00 | 25.50 | 64.33 | 57.00 | | 77.33 | 79.00 | 83.25 | 62.90 | 100 |
| CVn | 23.00 | 19.00 | 22.75 | 19.50 | 32.00 | 31.25 | 41.67 | 44.00 | 47.33 | 35.25 | 27.00 | 18.25 | 5.67 | | | 1.00 | 20.00 | 11.00 | 29.50 | 26.00 | 8.25 | 10.00 | 9.00 | 8.00 | 52.00 | 47.50 | | 68.33 | 74.00 | 83.25 | 30.17 | 47.96 |
| CVs | 13.00 | 11.67 | 34.25 | 38.50 | 44.50 | 55.50 | 45.33 | 52.25 | 57.00 | 61.25 | 61.33 | 56.75 | 54.67 | | | 35.50 | 39.00 | 25.75 | 26.00 | 34.50 | 27.75 | 30.00 | 26.00 | 17.50 | 12.33 | 9.50 | | 9.00 | 5.00 | 0.00 | 32.73 | 52.04 |
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