Revised Group Sunspot Number for 1640, 1652, and 1741

TL;DR

This paper revises historical solar activity data by correcting the annual group sunspot numbers for 1640, 1652, and 1741, providing more accurate estimates based on original observations.

Contribution

It introduces revised and more accurate sunspot numbers for specific years, improving historical solar activity records.

Findings

Revised sunspot number for 1640 is 15.2

Revised sunspot number for 1652 is 1.8

Revised sunspot number for 1741 is 27.3

Abstract

Some studies have shown that our knowledge on solar activity in the years 1640, 1652, and 1741 can be improved. In this contribution, we revise the annual group sunspot numbers for these years from original observations. For the years 1640, 1652 and 1741, we have obtained the corrected values 15.2, 1.8, and 27.3, respectively (instead of the original values 15.0, 4.0, and 57.7).