Provisional International monthly mean Sunspot Number for
April 2012 : 55.2 (fifty-five point two)


Maximum : 108 on 20 // Minimum : 9 on 9

Provisional daily International Sunspot Numbers for April 2012 : 

      1.. 42    6.. 34   11.. 19   16.. 39   21..104   26.. 75
      2.. 51    7.. 19   12.. 37   17.. 51   22.. 94   27.. 68
      3.. 46    8.. 16   13.. 35   18.. 72   23.. 89   28.. 72
      4.. 41    9..  9   14.. 33   19.. 95   24.. 86   29.. 71
      5.. 34   10.. 10   15.. 58   20..108   25.. 81   30.. 67

70 cooperating stations on May 1, 10 UT

Predictions of the monthly smoothed Sunspot Number using the last
provisional value, calculated for October 2011 :  59.9 (+-5%)

            SM    CM                 SM    CM                 SM    CM     

2011 Nov    63    62     2012 May    75    79     2012 Nov    94    92
     Dec    68    64          Jun    78    82          Dec    97    93
2012 Jan    66    67          Jul    81    84     2013 Jan   101    93
     Feb    68    71          Aug    84    86          Feb   103    94
     Mar    70    73          Sep    86    88          Mar   105    93
     Apr    73    76          Oct    90    90          Apr   105    92

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