Data Files

Each file can be downloaded by clicking on the grey button corresponding to the chosen format. All files are in ASCII text and can be opened in any text editor. CSV files allow direct import in various applications, like spreadsheets.

Data Credits: The Sunspot Number data can be freely downloaded. However, we request that proper credit to the WDC-SILSO is explicitely included in any publication using our data (paper article or book, on-line Web content, etc.), e.g.: "Source: WDC-SILSO, Royal Observatory of Belgium, Brussels".

Total sunspot number

  • Daily total sunspot number [1/1/1818 - now]
  • Monthly mean total sunspot number (+ 13-month smoothed numbers [1/1749 - now]
  • Yearly mean total sunspot number [1700 - now]
  • Daily Estimated Sunspot Number

    Hemispheric sunspot numbers

  • Daily total and North/South sunspot numbers (yearly files) [1/1/1992 - now]
  • Daily total and North/South sunspot numbers (single file) [1/1/1992 - now]
  • Monthly mean North-South sunspot numbers [1/1992 - now]
  • 12-month forecasts of the monthly sunspot number

  • Standard curves method (Waldmeier)
  • Combined method (Denkmayr - Cugnon)
  • Improved standard method prediction (Kalman)
  • Improved combined method prediction (Kalman)
  • Improved McNish & Lincoln method prediction (Kalman)

  • For additonal information, contact Frédéric Clette (E_mail: )
    Royal Observatory of Belgium Av. Circulaire, 3 - B-1180 Brussels, Belgium