- How come there are data with values between 0 and 11?
- Why counting sunspots by eye nowadays, in the space era?
- Ins't a visual sunspot number completely subjective compared to modern quantitative indices?
- Why is the International Sunspot Number always lower than simultaneous Wolf numbers published by other sources ? (The 0.6 factor)
- What is the special role of the pilot station ? (Specola Solare Ticinese, Locarno)
- What does smoothed monthly mean sunspot number actually mean?
- How is the yearly mean sunspot number calculated?
- Which time tag should be attached to each daily International Sunspot Number?
- Who can contribute as an observer to the SILSO sunspot network?
- What are the motivations and personal benefits to be a SILSO observer ?
- Will the original Sunspot Number data serie (V1.0) be continued in the future?