Since 1981, the Royal Observatory of Belgium harbours the Sunspot Index Data
center, the World data center for the Sunspot Index.
Recently, the Space Weather forecast center of Paris-Meudon
was transferred and added to the activities of the SIDC. Moreover, a complete
archive of all images of the SOHO instrument EIT has become available at the
SIDC. Given all these extensions, the new style SIDC has become a 'Solar
Influences Data analysis Center' that analyses the solar activity and provides
services on three different time scales:
1. Fast warnings and real time monitoring. As the Regional Warning center (RWC) for Western Europe of the International Space Environment Service (ISES), the SIDC collects and redistributes solar, geomagnetic, and ionospheric data in Western Europe. Short-term predictions (3 days) and alerts are produced on a daily basis.
2. Forecasts and middle term analysis. The SIDC takes care of the calculation of a sunspot index, called the International Sunspot Number. We compute and broadcast the daily, monthly, yearly international sunspot numbers, with middle range predictions (up to 12 months).
3. Post-event analysis and long term solar cycle analysis. Since the launch of SOHO, EIT offers a global view of the EUV corona over the whole rising phase of the solar activity cycle. Such a long-duration data series is unprecedented and allows the study of the evolution over the solar cycle of objects classes such as active regions, coronal holes, coronal mass ejections or flares.