5312 20210301153231.0 10.1017/S174392131900396X DOI SCART-2021-0074 Clette, Frédéric Sunspot and Group Number: Recent advances from historical data 2020 Due to its unique 400-year duration, the sunspot number is a central reference for understanding the long-term evolution of solar activity and its influence on the Earth environment and climate. Here, we outline current data recovery work. For the sunspot number, we find historical evidence of a disruption in the source observers occurring in 1947–48. For the sunpot group number, recent data confirm the clear southern predominance of sunspots during the Maunder Minimum, while the umbra-penumbra ratio is similar to other epochs. For the Dalton minimum, newly recovered historical observations confirm a higher activity level than in a true Grand Minimum. STCE Sunspots Solar cycle Historical data Vaquero, José M. Cruz Gallego, María Lefèvre, Laure Proceedings of the IAU 14 2020 Symposium A30 156-159 frederic.clette@observatoire.be https://www.cambridge.org/core/journals/proceedings-of-the-international-astronomical-union/article/abs/sunspot-and-group-number-recent-advances-from-historical-data/F1412DB008831540E33661AFB5241D6A published in NONREF