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Periodicities of the de la rue Sunspot Area Measurements |
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| Authors: | Vaquero JM Gallego MC Sánchez-bajo F |
| Institution: | 1. Departamento de Física, Escuela Politécnica, Universidad de Extremadura, Avda de la Universidad s/n, 10071, Cáceres, Spain 2. Departamento de Física, Facultad de Ciencias, Universidad de Extremadura, Ctra de Elvas s/n, 06071, Badajoz, Spain 3. Departamento de Electrónica e Ingeniería Electromecánica, Escuela de Ingenierías Industriales, Universidad de Extremadura, Ctra de Elvas s/n, 06071, Badajoz, Spain |
| Abstract: | In the 19th century De la Rue, Stewart, and Loewy carried out a compilation of drawings and photographs of the solar sunspots corresponding to the interval 1832–1868. Using these drawings and photographs, they determined fortnightly values of the percentage of the solar photosphere covered by the sunspots. In this work, we have performed a spectral analysis of these data in order to determine possible periodic signals. In addition to the 11-year solar cycle, short cycles of about 330 days and 30–50 days have been recovered, lacking the 150–160 days period discovered by other authors using several solar activity indicators. |
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