Lefèvre, Laure ; Mampaey, Benjamin ; Kalugodu, Chandrashekhar ; Valliapan, Pavai ; Delouille, Véronique ; Ritter, Christian ; Hayakawa, Hisashi ; Arlt, Rainer

Poster presented at AGU Fall Meeting, New Orleans, USA on 2025-12-16

Abstract: The sunspot number is the primary record for solar variability over the last 400 years and constitutes a benchmark in solar/stellar variability studies and especially the Earth climate. While the Sunspot Number has been recalibrated recently (Clette, 2016), it can still be improved with a full reconstruction from the raw data. Now that more and more historical raw sunspot data are being made available through a collective effort of the community, it is time to make it accessible to the many researchers and users outside of the sunspot community. FARSuN will make the raw historical sunspot data [1610-1980] Findable and Accessible for all users. The project gathers, interprets and valorizes the data, where the latter includes data pre-processing, quality assessment and standardization, as well as advocating data to end users. A detailed statistical study will provide quality criteria for these historical data, and the most pertinent criteria will be included in metadata describing the dataset. The output of this project will be a compilation of historical sunspot numbers that will be made available via standard VOtools and the data will be FAIR-compliant. Making these validated historical sunspot data collections FAIR will allow solar physicists, Earth-climate modellers, experts in statistics, or anyone with a keen interest in solar variability, to analyse this unique natural record, increase awareness of the public of the effects of solar variability on Earth and thus feed future science in the service of society.

Funding: FARSUN - SUNRISE/FARSUN - SUNRISE/FARSUN - SUNRISE