Sunspot Number

Since July 1st 2015, the original Sunspot number data have been replaced by a new entirely revised data series. On this occasion, the data are presented in a new array of files, containing additional values that were not present in the original series. For proper tracking of those changes, the present version is numbered 2.0.

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".

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