In 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.

1876 年，阿尔弗雷德·沃尔夫 (Alfred Wolfer) 开始与鲁道夫·沃尔夫 (Rudolf Wolf) 一起观测太阳并记录太阳黑子的特性。他们的观察结果成为构建太阳黑子数系列的基础。 1893 年沃尔夫去世后，沃尔夫成为太阳黑子数系列的主要观察者。尽管沃尔夫和沃尔夫的观测有近 17 年的重叠（1876-1893），但主要观察者从沃尔夫到沃尔夫的这种转变似乎导致了太阳黑子数系列的不一致，这主要是由于沃尔夫观测的不均匀性。为了解决这个问题，我们对 Mittheilungen（沃尔夫的日记）进行数字化并分析其表格数据集。这些期刊包括苏黎世天文台用来编制太阳黑子数系列 (SNV1) 的各个观测者的原始太阳黑子数据。这些数据集已被用作构建太阳黑子数 (SNV1) 系列第一版的源数据，但直到最近才可以通过数字方式访问它们来重新校准太阳黑子数系列。我们还从最近同期太阳黑子观测的档案调查中获取了外部数据集。在这项研究中，我们使用 Mittheilungen 数据集对涵盖 1816 年至 1944 年的太阳黑子数系列进行了新的重新校准，并使用四位主要观测者（Tevel、Schwabe、Weber 和 Wolfer）作为骨干。原始数据的可用性使我们能够识别确定不同观察者的记录之间的比例因子或\(k\)因子的问题，而且还可以使用现代技术进行交叉校准。我们对 1816 年至 1944 年的重建是采用受 Chatzistergos 等人启发的新颖方法进行的。 ( Astron. Astrophys . 602 , A69, 2017) 允许我们消除由于应用错误的\(k\)因子而导致的不一致。