Bošković's method for determining the axis and rate of solar rotation by observing sunspots in 1777

Fuente: arXiv
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Main Authors: Husak, Mirko, Brajša, Roman, Špoljarić, Dragan, Krajnović, Davor, Ruždjak, Domagoj, Skokić, Ivica, Roša, Dragan, Hržina, Damir
Format: Preprint
Published: 2025
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author Husak, Mirko
Brajša, Roman
Špoljarić, Dragan
Krajnović, Davor
Ruždjak, Domagoj
Skokić, Ivica
Roša, Dragan
Hržina, Damir
author_facet Husak, Mirko
Brajša, Roman
Špoljarić, Dragan
Krajnović, Davor
Ruždjak, Domagoj
Skokić, Ivica
Roša, Dragan
Hržina, Damir
contents In 1777 Ruđer Bošković observed sunspots, determined their positions and the solar rotation elements by his own methods briefly described here. We repeat his calculations of the mean solar time, sunspot positions, and solar rotation elements using both the Bošković's original equations and equations adapted for modern computers. We repeat the calculations using two values of the obliquity of the ecliptic, Bošković's, and an interpolated one. Using his 1777 observations, Bošković obtained the solar equator's inclination, ecliptic longitude of the ascending node, and sidereal and synodic rotation periods. We analyzed and compared these original Bošković results with our repeated calculations. Our results confirm the validity of Bošković's methods and the precision of his calculations. Additionally, the paper presents the solar differential rotation determination using all 1777 observations by Ruđer Bošković.
format Preprint
id arxiv_https___arxiv_org_abs_2502_15053
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Bošković's method for determining the axis and rate of solar rotation by observing sunspots in 1777
Husak, Mirko
Brajša, Roman
Špoljarić, Dragan
Krajnović, Davor
Ruždjak, Domagoj
Skokić, Ivica
Roša, Dragan
Hržina, Damir
Solar and Stellar Astrophysics
In 1777 Ruđer Bošković observed sunspots, determined their positions and the solar rotation elements by his own methods briefly described here. We repeat his calculations of the mean solar time, sunspot positions, and solar rotation elements using both the Bošković's original equations and equations adapted for modern computers. We repeat the calculations using two values of the obliquity of the ecliptic, Bošković's, and an interpolated one. Using his 1777 observations, Bošković obtained the solar equator's inclination, ecliptic longitude of the ascending node, and sidereal and synodic rotation periods. We analyzed and compared these original Bošković results with our repeated calculations. Our results confirm the validity of Bošković's methods and the precision of his calculations. Additionally, the paper presents the solar differential rotation determination using all 1777 observations by Ruđer Bošković.
title Bošković's method for determining the axis and rate of solar rotation by observing sunspots in 1777
topic Solar and Stellar Astrophysics
url https://arxiv.org/abs/2502.15053