Solar Activity Database
National Astronomical Observatory of Japan and its predecessor (Tokyo Astronomic al Observatory of the University of Tokyo) have been conducting observations of various activity indices of the sun. The peak of solar activity, indicated by numerous sunspots and frequent flare ex plosions, comes every 10-11 years. This periodicity is sometimes disturbed; for example in the 17-th century there was a period of about 50 years in which the solar activity was unusually low. In order to investigate such a long time scale variation of the sun, persistent observations of the sun and systematic accumulation of data are crucial.
We have made the following data available to the public. No restrictions apply for browsing the data. When you intend to publish an article based on these data, you are requested to contact us in advance.
STEP/S-RAMP Solar Optical Data On-Line
CAWSES Solar Optical Data On-Line
Solar Activity World Data Center
Quarterly Bulletin on Solar Activity (QBSA)
Sunspot Groups with Largest Areas (1874-2016)