The solar rotation in the period 1853-1870 from the sunspot catalogues of Carrington, Peters, and de la Rue

TL;DR

This study analyzes 19th-century sunspot data from Carrington, Peters, and de la Rue to understand solar rotation and compare observational results with existing models, revealing insights into historical solar activity.

Contribution

It provides a detailed analysis of historical sunspot data, fitting differential rotation laws and exploring relationships between sunspot areas and velocities, using recently digitized catalogs.

Findings

Consistent differential rotation profiles across observers

Correlation between sunspot areas and group velocities

Validation of historical data against modern models

Abstract

R. C. Carrington, C. H. F. Peters, and W. de la Rue observed the sunspots in the second half of the 19th century, determining their heliographic positions between 1853 and 1870, before the establishment of the solar program of the Royal Greenwich Observatory. The large tables of sunspot positions included in the catalogues published by these observers have recently been converted to a machine readable format. The present work analyses this data by calculating the sunspot group velocities for each observer. These results are then fitted with a differential rotation law to compare the data of the three observers with each other and with the results published by other authors. Finally, a study is made of the possible relationship between the sunspot group areas as determined by de la Rue and the corresponding sunspot group velocities.