Statistics of sunspot activity
April, 1991
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 | 139.00 | 142.17 | 191.80 | 188.33 | 238.57 | 252.71 | 211.86 | 180.71 | 213.57 | 260.17 | 252.00 | 287.00 | 266.00 | 323.33 | 284.14 | 251.83 | 217.20 | 233.17 | 186.50 | 226.50 | 162.00 | 98.00 | 89.14 | 57.71 | 69.80 | 99.25 | 106.29 | 167.00 | 174.43 | 180.86 | 191.70 | 100 |
| Wn | 94.00 | 86.50 | 102.40 | 88.67 | 106.00 | 104.00 | 98.00 | 90.57 | 95.29 | 97.33 | 98.00 | 139.60 | 167.00 | 189.00 | 156.29 | 145.50 | 123.40 | 115.50 | 79.00 | 80.00 | 55.00 | 33.17 | 10.43 | 1.57 | 10.40 | 25.63 | 21.29 | 30.86 | 42.00 | 48.00 | 84.48 | 44.07 |
| Ws | 45.00 | 55.67 | 89.40 | 99.67 | 132.57 | 148.71 | 113.86 | 90.14 | 118.29 | 162.83 | 154.00 | 147.40 | 99.00 | 134.33 | 127.86 | 106.33 | 93.80 | 117.67 | 107.50 | 146.50 | 107.00 | 64.83 | 78.71 | 56.14 | 59.40 | 73.63 | 85.00 | 136.14 | 132.43 | 132.86 | 107.22 | 55.93 |
| n | 4.29 | 4.17 | 7.00 | 8.33 | 11.43 | 13.43 | 11.86 | 11.86 | 14.57 | 17.17 | 14.50 | 14.00 | 11.60 | 13.17 | 11.86 | 9.00 | 7.20 | 8.00 | 8.17 | 10.67 | 8.17 | 5.67 | 5.71 | 4.00 | 5.00 | 7.38 | 7.00 | 9.71 | 9.71 | 10.71 | 9.51 | 100 |
| A | 0.71 | 1.17 | 1.80 | 0.67 | 2.14 | 2.43 | 2.14 | 1.29 | 2.71 | 4.33 | 1.50 | 1.60 | 0.80 | 1.67 | 2.43 | 2.33 | 0.80 | 1.00 | 0.33 | 1.50 | 0.83 | 0.50 | 1.86 | 1.43 | 1.20 | 2.25 | 1.29 | 1.57 | 0.29 | 1.14 | 1.52 | 16.02 |
| B | 0.43 | 0.00 | 0.80 | 2.00 | 2.71 | 3.14 | 2.29 | 2.43 | 4.14 | 3.50 | 4.00 | 2.60 | 2.00 | 2.67 | 1.57 | 1.00 | 1.60 | 2.17 | 2.50 | 3.00 | 3.50 | 2.33 | 2.86 | 1.43 | 1.80 | 2.13 | 1.57 | 2.57 | 2.86 | 2.71 | 2.28 | 23.94 |
| C | 0.00 | 0.17 | 0.20 | 1.83 | 2.29 | 2.43 | 2.14 | 3.29 | 2.14 | 3.00 | 1.75 | 2.40 | 2.40 | 2.33 | 1.14 | 1.33 | 2.20 | 2.00 | 1.17 | 1.00 | 0.83 | 1.50 | 1.00 | 1.14 | 1.20 | 1.38 | 1.00 | 1.29 | 1.29 | 3.29 | 1.64 | 17.22 |
| D | 1.43 | 0.67 | 1.20 | 1.83 | 2.29 | 2.71 | 2.71 | 3.14 | 3.57 | 3.33 | 3.50 | 2.80 | 1.60 | 2.33 | 2.71 | 1.83 | 1.00 | 1.17 | 1.17 | 1.67 | 0.33 | 0.33 | 0.00 | 0.00 | 0.20 | 0.25 | 0.57 | 0.57 | 1.57 | 0.71 | 1.57 | 16.55 |
| E | 1.14 | 0.67 | 1.60 | 0.83 | 0.29 | 0.14 | 0.00 | 0.00 | 0.00 | 0.00 | 1.25 | 0.80 | 0.60 | 1.00 | 0.86 | 0.83 | 1.00 | 0.83 | 1.17 | 0.83 | 0.67 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.86 | 0.57 | 0.14 | 0.54 | 5.64 |
| F | 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 | 0.17 | 0.43 | 0.50 | 0.20 | 0.17 | 0.33 | 0.33 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.07 | 0.75 |
| G | 0.43 | 1.50 | 0.80 | 0.83 | 1.00 | 0.86 | 0.86 | 0.14 | 0.29 | 0.50 | 0.25 | 2.00 | 2.40 | 1.50 | 1.29 | 1.00 | 0.40 | 0.50 | 0.83 | 1.50 | 1.50 | 0.50 | 0.00 | 0.00 | 0.00 | 0.00 | 0.71 | 1.00 | 1.43 | 1.00 | 0.83 | 8.77 |
| H | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.17 | 0.00 | 0.00 | 0.20 | 0.00 | 0.00 | 0.00 | 0.00 | 0.17 | 0.17 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.14 | 0.14 | 0.03 | 0.35 |
| I | 0.14 | 0.00 | 0.60 | 0.33 | 0.71 | 1.71 | 1.71 | 1.57 | 1.71 | 2.33 | 2.25 | 1.80 | 1.60 | 1.50 | 1.43 | 0.17 | 0.00 | 0.00 | 0.50 | 0.83 | 0.50 | 0.50 | 0.00 | 0.00 | 0.60 | 1.38 | 1.86 | 1.86 | 1.57 | 1.57 | 1.02 | 10.78 |
| x | 1.14 | 1.17 | 2.60 | 2.67 | 4.86 | 5.57 | 4.43 | 3.71 | 6.86 | 7.83 | 5.50 | 4.20 | 2.80 | 4.33 | 4.00 | 3.33 | 2.40 | 3.17 | 2.83 | 4.50 | 4.33 | 2.83 | 4.71 | 2.86 | 3.00 | 4.38 | 2.86 | 4.14 | 3.14 | 3.86 | 3.80 | 39.96 |
| r | 0.00 | 0.00 | 0.00 | 0.17 | 0.14 | 0.57 | 1.14 | 0.86 | 1.00 | 2.00 | 1.00 | 1.20 | 1.00 | 1.17 | 0.14 | 0.33 | 0.20 | 0.17 | 0.33 | 0.83 | 0.50 | 0.33 | 0.00 | 0.14 | 0.20 | 0.38 | 0.43 | 0.43 | 0.86 | 1.00 | 0.55 | 5.79 |
| s | 0.14 | 0.33 | 0.60 | 1.50 | 2.00 | 3.29 | 1.86 | 4.29 | 4.00 | 2.50 | 2.75 | 2.60 | 2.00 | 3.17 | 2.86 | 0.50 | 0.60 | 0.67 | 0.83 | 1.50 | 0.33 | 0.83 | 0.71 | 0.71 | 1.20 | 1.75 | 2.71 | 2.14 | 1.43 | 1.86 | 1.72 | 18.11 |
| a | 1.57 | 1.83 | 2.00 | 2.67 | 2.71 | 2.71 | 4.29 | 3.00 | 2.71 | 4.50 | 5.00 | 5.00 | 3.60 | 2.17 | 2.43 | 1.67 | 2.00 | 1.83 | 3.00 | 3.17 | 2.83 | 1.67 | 0.29 | 0.29 | 0.60 | 0.88 | 1.00 | 3.00 | 3.43 | 3.00 | 2.49 | 26.23 |
| h | 0.29 | 0.17 | 0.00 | 0.00 | 0.14 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.20 | 0.17 | 0.00 | 0.17 | 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 | 0.04 | 0.40 |
| k | 1.14 | 0.67 | 1.80 | 1.33 | 1.57 | 1.29 | 0.14 | 0.00 | 0.00 | 0.33 | 0.25 | 1.00 | 2.00 | 2.17 | 2.43 | 3.00 | 2.00 | 2.17 | 1.17 | 0.67 | 0.17 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.86 | 1.00 | 0.90 | 9.51 |
| x | 0.86 | 1.17 | 2.40 | 1.00 | 2.86 | 4.14 | 3.86 | 2.86 | 4.43 | 6.83 | 3.75 | 3.40 | 2.60 | 3.17 | 3.86 | 2.50 | 0.80 | 1.17 | 1.00 | 2.33 | 1.33 | 1.00 | 1.86 | 1.43 | 1.80 | 3.63 | 3.14 | 3.43 | 2.00 | 2.86 | 2.58 | 27.14 |
| o | 1.57 | 2.33 | 2.80 | 5.67 | 7.00 | 8.57 | 7.71 | 8.86 | 10.14 | 9.83 | 9.50 | 9.00 | 7.60 | 7.33 | 5.71 | 5.00 | 4.60 | 5.33 | 5.00 | 7.00 | 5.83 | 4.67 | 3.86 | 2.29 | 3.00 | 3.75 | 3.71 | 5.29 | 6.71 | 7.14 | 5.89 | 61.97 |
| i | 1.86 | 0.67 | 1.40 | 1.67 | 1.43 | 0.71 | 0.14 | 0.14 | 0.00 | 0.50 | 1.25 | 1.40 | 0.80 | 2.33 | 1.86 | 1.17 | 1.20 | 1.17 | 1.67 | 1.17 | 1.00 | 0.00 | 0.00 | 0.29 | 0.20 | 0.00 | 0.14 | 1.00 | 1.00 | 0.71 | 0.90 | 9.42 |
| c | 0.00 | 0.00 | 0.40 | 0.00 | 0.14 | 0.00 | 0.14 | 0.00 | 0.00 | 0.00 | 0.00 | 0.20 | 0.60 | 0.33 | 0.43 | 0.33 | 0.60 | 0.33 | 0.50 | 0.17 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.14 | 1.47 |
| CV | 103.14 | 83.00 | 134.00 | 130.83 | 154.00 | 155.00 | 112.71 | 118.14 | 125.43 | 140.33 | 152.25 | 184.60 | 194.80 | 213.17 | 210.57 | 184.83 | 134.20 | 138.17 | 130.17 | 130.83 | 73.83 | 40.00 | 17.71 | 15.43 | 25.00 | 36.00 | 60.57 | 87.43 | 125.57 | 110.86 | 117.42 | 100 |
| CVn | 60.71 | 45.50 | 70.40 | 75.00 | 79.14 | 74.29 | 59.14 | 50.71 | 60.43 | 64.17 | 69.25 | 102.00 | 136.60 | 124.83 | 110.71 | 96.67 | 88.40 | 83.00 | 77.67 | 60.17 | 38.00 | 18.33 | 1.43 | 0.14 | 4.20 | 10.63 | 18.71 | 21.71 | 35.57 | 41.86 | 59.31 | 50.51 |
| CVs | 42.43 | 37.50 | 63.60 | 55.83 | 74.86 | 80.71 | 53.57 | 67.43 | 65.00 | 76.17 | 83.00 | 82.60 | 58.20 | 88.33 | 99.86 | 88.17 | 45.80 | 55.17 | 52.50 | 70.67 | 35.83 | 21.67 | 16.29 | 15.29 | 20.80 | 25.38 | 41.86 | 65.71 | 90.00 | 69.00 | 58.11 | 49.49 |
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