000007271 001__ 7271
000007271 005__ 20250109112306.0
000007271 0247_ $$2DOI$$a10.1007/s11207-024-02261-7 
000007271 037__ $$aSCART-2025-0025
000007271 100__ $$aBhattacharya, S.
000007271 245__ $$aRudolf Wolf to Alfred Wolfer: The Transfer of the Reference Observer in the International Sunspot Number Series (1876–1893)
000007271 260__ $$c2024
000007271 520__ $$aIn 1876, Alfred Wolfer started observing the Sun and recording the properties of sunspots alongside Rudolf Wolf. Their observations became the basis for the construction of the sunspot-number series. After Wolf's death in 1893, Wolfer became the primary observer for the sunspot-number series. Even though the observations of Wolf and Wolfer had an overlap of almost 17 years (1876–1893), this shift of primary observer from Wolf to Wolfer seems to have led to inconsistencies in the sunspot-number series, primarily due to inhomogeneities in Wolf's observations. To address this issue we digitise Mittheilungen (Wolf's journals) and analyse their tabulated datasets. These journals include the raw sunspot data from various observers that the Zürich Observatory used to compile the sunspot number series (SNV1). These datasets have been used as source data for the construction of the first version of the sunspot number (SNV1) series, but they were not digitally accessible for a recalibration of the sunspot-number series until recently. We have also acquired external datasets from recent archival investigations for contemporaneous sunspot observations. In this study, we use the Mittheilungen dataset to produce a new recalibration of the sunspot-number series covering 1816–1944, using four major observers (Tevel, Schwabe, Weber and Wolfer) as backbones. The availability of the raw data allows us to identify issues in the determination of the scaling factors or k-factors, between the records of different observers, but also the use of modern techniques for cross-calibrations. Our reconstruction for the years 1816–1944 is carried out with a novel method inspired by Chatzistergos et al. (Astron. Astrophys. 602, A69, 2017) allowing us to eliminate inconsistencies that resulted from the application of erroneous k-factors.
000007271 536__ $$aFARSUN/$$cFARSUN/$$fFARSUN
000007271 594__ $$aSTCE
000007271 700__ $$aLefèvre, L.
000007271 700__ $$aChatzistergos, T.
000007271 700__ $$aHayakawa, H.
000007271 700__ $$aJansen, M.
000007271 773__ $$c45$$n4$$pSolar Physics$$v299$$y2024
000007271 8560_ $$flaure.lefevre@ksb-orb.be
000007271 905__ $$apublished in
000007271 980__ $$aREFERD