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Definitive or provisional value / Valeur définitive ou provisoire

Monthly mean sunspot number since 1749 (taches solaires) - SILSO data, Royal Observatory of Belgium, Brussels

Date (month) / Date (mois)
Date in fraction of year / Date en fraction de l'année
Monthly mean total sunspot number
Monthly mean / Moyenne mensuelle
Number of observations / Nombre d'observations
Definitive or provisional value / Valeur définitive ou provisoire
1
January 1749
1,749.042
96.7
-1
-1
1
2
February 1749
1,749.123
104.3
-1
-1
1
3
March 1749
1,749.204
116.7
-1
-1
1
4
April 1749
1,749.288
92.8
-1
-1
1
5
May 1749
1,749.371
141.7
-1
-1
1
6
June 1749
1,749.455
139.2
-1
-1
1
7
July 1749
1,749.538
158
-1
-1
1
8
August 1749
1,749.623
110.5
-1
-1
1
9
September 1749
1,749.707
126.5
-1
-1
1
10
October 1749
1,749.79
125.8
-1
-1
1
11
November 1749
1,749.874
264.3
-1
-1
1
12
December 1749
1,749.958
142
-1
-1
1
13
January 1750
1,750.042
122.2
-1
-1
1
14
February 1750
1,750.123
126.5
-1
-1
1
15
March 1750
1,750.204
148.7
-1
-1
1
16
April 1750
1,750.288
147.2
-1
-1
1
17
May 1750
1,750.371
150
-1
-1
1
18
June 1750
1,750.455
166.7
-1
-1
1
19
July 1750
1,750.538
142.3
-1
-1
1
20
August 1750
1,750.623
171.7
-1
-1
1
21
September 1750
1,750.707
152
-1
-1
1
22
October 1750
1,750.79
109.5
-1
-1
1
23
November 1750
1,750.874
105.5
-1
-1
1
24
December 1750
1,750.958
125.7
-1
-1
1
25
January 1751
1,751.042
116.7
-1
-1
1
26
February 1751
1,751.123
72.5
-1
-1
1
27
March 1751
1,751.204
75.5
-1
-1
1
28
April 1751
1,751.288
94
-1
-1
1
29
May 1751
1,751.371
101.2
-1
-1
1
30
June 1751
1,751.455
84.5
-1
-1
1
31
July 1751
1,751.538
110.5
-1
-1
1
32
August 1751
1,751.623
99.7
-1
-1
1
33
September 1751
1,751.707
39.2
-1
-1
1
34
October 1751
1,751.79
38.7
-1
-1
1
35
November 1751
1,751.874
47.5
-1
-1
1
36
December 1751
1,751.958
73.3
-1
-1
1
37
January 1752
1,752.042
58.3
-1
-1
1
38
February 1752
1,752.124
83.3
-1
-1
1
39
March 1752
1,752.206
118.3
-1
-1
1
40
April 1752
1,752.29
98.8
-1
-1
1
41
May 1752
1,752.373
99.5
-1
-1
1
42
June 1752
1,752.456
66
-1
-1
1
43
July 1752
1,752.54
130.7
-1
-1
1
44
August 1752
1,752.624
48.8
-1
-1
1
45
September 1752
1,752.708
45.2
-1
-1
1
46
October 1752
1,752.791
77.7
-1
-1
1
47
November 1752
1,752.874
62.7
-1
-1
1
48
December 1752
1,752.958
66.7
-1
-1
1
49
January 1753
1,753.042
73.3
-1
-1
1
50
February 1753
1,753.123
53.3
-1
-1
1
51
March 1753
1,753.204
76.2
-1
-1
1
52
April 1753
1,753.288
63.3
-1
-1
1
53
May 1753
1,753.371
60
-1
-1
1
54
June 1753
1,753.455
52.8
-1
-1
1
55
July 1753
1,753.538
36.7
-1
-1
1
56
August 1753
1,753.623
65
-1
-1
1
57
September 1753
1,753.707
46.7
-1
-1
1
58
October 1753
1,753.79
41.7
-1
-1
1
59
November 1753
1,753.874
33.3
-1
-1
1
60
December 1753
1,753.958
11.2
-1
-1
1
61
January 1754
1,754.042
0
-1
-1
1
62
February 1754
1,754.123
5
-1
-1
1
63
March 1754
1,754.204
2.8
-1
-1
1
64
April 1754
1,754.288
22.8
-1
-1
1
65
May 1754
1,754.371
34.5
-1
-1
1
66
June 1754
1,754.455
44.5
-1
-1
1
67
July 1754
1,754.538
31.3
-1
-1
1
68
August 1754
1,754.623
20.5
-1
-1
1
69
September 1754
1,754.707
13.7
-1
-1
1
70
October 1754
1,754.79
40.2
-1
-1
1
71
November 1754
1,754.874
22
-1
-1
1
72
December 1754
1,754.958
7
-1
-1
1
73
January 1755
1,755.042
17
-1
-1
1
74
February 1755
1,755.123
18.7
-1
-1
1
75
March 1755
1,755.204
11.3
-1
-1
1
76
April 1755
1,755.288
10.8
-1
-1
1
77
May 1755
1,755.371
0
-1
-1
1
78
June 1755
1,755.455
0
-1
-1
1
79
July 1755
1,755.538
14.3
-1
-1
1
80
August 1755
1,755.623
5.3
-1
-1
1
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