Early American sunspot drawings from the “year without a summer”

Abstract

A set of sunspot drawings from the early nineteenth century were discovered in the journals of the Reverend Jonathan Fisher. These drawings were made during a time when abnormally cold weather caused crops in New England to fail due to intermittent frost throughout the summer months of 1816, normally referred to as the “year without a summer.” Global changes in weather patterns were the result of the Mount Tambora volcano eruption. Since this association was unknown at the time, there was speculation that the Sun was the cause inspiring the Reverend Fisher to monitor changes in sunspots during the summer of 1816 and continuing into 1817. These sunspot drawings for the summer of 1816 overlap the solar observations of Sir William Hershel.

Sunspot Observations Made by Hallaschka During the Dalton Minimum

“…Lindener, as Hallaschka, also registered 7 sunspot groups for that same day (Figure 3). Figure 3 contains information about the raw sunspot group counts made by all observers included in Vaquero et al (2016) for the period 1813-1818 along with the sunspot observations made by Hallaschka, studied in this work, and Fisher, recently published by Denig and McVaugh (2017). For the remaining observations, the number of sunspot groups observed by Hallaschka is similar than those observed by other astronomers (Figure 3).…”

“…For the remaining observations, the number of sunspot groups observed by Hallaschka is similar than those observed by other astronomers (Figure 3). The observations made by Fisher, recovered by Denig and McVaugh (2017), are composed by 25 sunspot drawings.…”

“…Therefore, the incorporation to the database of group counts of new information about sunspot records not previously published is important to improve the temporary coverage of this period. Thus, the recovery of a sunspot drawing made by Iwahashi Zenbei (Hayakawa et al, 2018) on 26 August 1793 and an undated one, during the decline phase of the Solar Cycle 4, and a set of 25 drawings by Jonathan Fisher (Denig and McVaugh, 2017) We found sunspot observations performed by Cassian Hallaschka in 1814 and 1816 (shortly before the maximum of the Solar Cycle 6) which have not yet been included in sunspot studies. The aim of this work is to present these solar observations and to contribute to improve the reconstruction of solar activity of the past, in particular, of the Dalton minimum.…”

Thaddäus Derfflinger’s Sunspot Observations during 1802–1824: A Primary Reference to Understand the Dalton Minimum

“…Excluding the apparent spotless days, we have also revised 7 observational dates, eliminated 8 observational dates, and added 7 observational dates against the register in the existing dataset (Hoyt and Schatten, 1998;Vaquero et al, 2016) and additional sunspot observations by Fisher (Denig and McVaugh, 2017) and Hallaschka (Carrasco et al, 2018). Hoyt and Schatten, 1998;Vaquero et al, 2016).…”

“…Revised sunspot group number of Derfflinger (blue diamond in the summary manuscript and red cross in the logbooks) contextualized upon the sunspot group number of the existing observers (black dot:Vaquero et al, 2016) and additional sunspot observations by Fisher (gray triangle:Denig and McVaugh, 2017) and Hallaschka (green triangle:Carrasco et al, 2018).InFigure 5, we have incorporated the sunspot group number in Derfflinger's summary manuscript and logbook as they are and contextualised them upon the existing sunspot group number by) Thaddäus Derfflinger's sunspot observations during 1802-1824, The Astrophysical Journal, doi: 10.3847/1538 contemporary observers. The summary manuscript and logbooks occasionally provide observations with different group number and observations on different days.…”