On the Determination of the Solar Rotation Elements i, {\Omega} and Period using Sunspot Observations by Ru{\dj}er Bo\v{s}kovi\'c in 1777

TL;DR

This paper revisits Ruder Bošković's 1777 sunspot observations and calculations of solar rotation, comparing his methods and results with modern astronomy to understand historical and scientific context.

Contribution

It reproduces Bošković's original solar rotation calculations from 1777 and analyzes their accuracy and relevance to modern astronomy.

Findings

Reproduced Bošković's calculations with similar results.

Analyzed input errors and their impact on the calculations.

Discussed the historical significance of Bošković's methods.

Abstract

In September 1777, Ru{\dj}er Bo\v{s}kovi\'c observed sunspots for six days. Based on these measurements, he used his own methods to calculate the elements of the solar rotation, the longitude of the node, the inclination of the solar equator and the period. He published a description of the methods, the method of observation and detailed instructions for calculations in the second chapter of the fifth part of the Opera in 1785. In this paper, Bo\v{s}kovi\'c original calculations and repeated calculations by his procedure are published. By analysing the input quantities, procedures, and results, the input quantities of the error, and the calculation results are discussed. The reproduction of Bo\v{s}kovi\'c calculations is successfully reproduced and we obtained very similar results. The conclusion proposes a relationship of Bo\v{s}kovi\'c research with modern astronomy.