Where to find the International Sunspot Number?

The SIDC provides the International Sunspot Number (ISN) in different forms and on different time scales: estimated, provisional, definitive, daily, monthly, monthly smoothed, yearly, ASCII, graphs. The choice is up to you.

We give overview of all kinds of data, direct links and how to reach the link.
The sunspot number clarified Text in main frame: news items
ISN in a graph Webpage in left menu: sunspots-graphs
ISN in numbers, ASCII-files webpage in left menu: sunspots-data
ASCII-files: explanation Readme in left menu: sunspots-data
in main frame: Readme file
Graphs, Numbers all at once Ftp site no link available on the webpages
Bulletins additional space weather info
daily, weekly, monthly versions
in left menu: bulletins

The graph (click for a bigger version) gives an overview of the daily, monthly, monthly smoothed and yearly ISN from 1700 up to 2009. For the first part of the 18th century, our archive includes only yearly numbers. From January 1749, the time resolution ranges up to a month, the monthly smoothed is plotted from July 1749. While from Jan 01, 1818, we have daily numbers with a complete coverage from 1849. As time progresses, the available time resolution becomes smaller. Only in the last part of the graph, the provisional numbers are used: the monthly smoothed number is provisional from 6 months before the last plotted point, i.e. June 2008, the monthly and daily number is provisional from Dec 2008. Prior, the definitive data are plotted.  



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