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 archive |
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. 
