Extended hemispheric sunspot numbers
A catalogue consisting of Hemispheric Sunspot Numbers from 1874-2020
Reconstructed hemispheric sunspot numbers extending the base international hemispheric sunspot numbers before 1992. This series is based on hemispheric sunspot numbers from the Kanzelhöhe and Skalnate-Pleso Observatories back to 1945, and on total sunspot areas from the Greenwich photographic catalogue back to 1874. Any use of this data set should include the citation of the original reference below.
Daily Hemispheric Sunspot Data (1874-05-01 to 2020-10-31)
Monthly Mean and Smoothed Hemispheric Data (1874-05 to 2020-10)
Astrid M.Veronig, Shantanu Jain, Tatiana Podladchikova, Werner Pötzi, Frédéric Clette, 2021: Hemispheric Sunspot Numbers 1874-2020 Astronomy & Astrophysics, Vol. 652, A56, DOI 10.1051/0004-6361/202141195 https://www.aanda.org/articles/aa/full_html/2021/08/aa41195-21/aa41195-21.html