Provisional International monthly mean Sunspot Number for
April 2013 : 72.4 (seventy-two point four)


Maximum : 101 on 30 // Minimum : 53 on 1

Provisional daily International Sunspot Numbers for April 2013 : 

      1.. 53    6.. 76   11.. 85   16.. 63   21.. 63   26.. 71
      2.. 66    7.. 85   12.. 84   17.. 64   22.. 60   27.. 72
      3.. 68    8.. 82   13.. 79   18.. 57   23.. 55   28.. 69
      4.. 63    9.. 92   14.. 74   19.. 59   24.. 66   29.. 95
      5.. 77   10.. 94   15.. 63   20.. 61   25.. 75   30..101

70 cooperating stations on May 1, 10 UT

Predictions of the monthly smoothed Sunspot Number using the last
provisional value, calculated for October 2012 :  58.6 (+-5%)

            SM    CM                 SM    CM                 SM    CM     

2012 Nov    57    60     2013 May    48    75     2013 Nov    43    90
     Dec    56    64          Jun    47    78          Dec    43    88
2013 Jan    54    67          Jul    46    81     2014 Jan    42    87
     Feb    52    70          Aug    45    83          Feb    41    86
     Mar    50    72          Sep    45    86          Mar    41    85
     Apr    49    74          Oct    44    89          Apr    40    84

SM : SIDC classical method : based on an interpolation of Waldmeier's
standard curves; the estimated error ranges from 7% (first month) to
35% (last month)
CM : Combined method : the combined method is a regression technique
coupling a dynamo-based estimator with Waldmeier's idea of standard
curves, due to K. Denkmayr.
ref. : K. Denkmayr, P. Cugnon, 1997 : "About Sunspot Number Medium-Term
Predictions", in "Solar-Terrestrial Prediction Workshop V", eds.
G. Heckman et al., Hiraiso Solar Terrestrial Research Center, Japan, 103