Eric Strach: Four Decades of Detailed Synoptic Solar Observations (1969‐2008)

Abstract

Eric H. Strach (1914‐2011) studied medicine at University of Prague and graduated in 1938. Strach dedicated a great part of his life to astronomy becoming a consistent and meticulous observer. He joined the Liverpool Astronomical Association and British Astronomical Association during the 1960s and obtained two recognitions as proof of his great work in solar physics: the BAA's Merlin Medal and Gift in 1999 and Walter Goodacre Medal and Gift, 10 years later. Strach recorded four decades (1969‐2008) of systematic solar records in his observation notebooks although he started his observations from the late 1950s. In this work, we document the valuable effort made by Strach in getting four decades of solar records and the importance of this kind of long observation series for studies of space weather and climate. We present the sunspot group number series according to Strach's data and a long observation series of prominences recorded by Strach.

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

“…Further, recent revisions of sunspot number based on historical documents require us to re-evaluate the solar activity for a longer time span (Clette and Lefevre, 2016;Vaquero et al, 2016). Thaddäus Derfflinger's sunspot observations during 1802-1824, The Astrophysical Journal, doi: 10.3847/1538-4357/ab65c9 et al, 2007Arlt, 2008Arlt, , 2009Arlt, , 2018Hayakawa et al, 2018aHayakawa et al, , 2018bCarrasco et al, 2015Carrasco et al, , 2016Carrasco et al, , 2018Carrasco et al, , 2019bDenig and McVaugh, 2017), remove apparent continuous spotless days (Vaquero, 2007;Vaquero et al, 2016), and revise observations based on modern viewpoints (Vaquero et al, 2016;Svalgaard, 2017;Hayakawa et al, 2018d;Arlt et al, 2013Arlt et al, , 2016Fujiyama et al, 2019;Karoff et al, 2019;Jørgensen et al, 2019;Pevtsov et al 2019). Based on these revisions, a long-term variation of solar activity was evaluated utilising multiple methodologies (Svalgaard and Schatten, 2016;Usoskin et al, 2016;Clette and Lefevre, 2016;Chatzistergos et al, 2017).…”

Sunspot observations by Hisako Koyama: 1945–1996

“…While observations were conducted over many decades in various institutional observatories such as Greenwich (Willis et al, 2013(Willis et al, , 2016a(Willis et al, , 2016b, Debrecen (Baranyi et al, 2016;Győri et al, 2017), or Mount Wilson (Lefèvre et al, 2005Pevtsov et al, 2019), long-term observations at smaller observatories by individual astronomers -frequently skilled amateur observers -are of particular importance in terms of stability. Indeed, such sunspot time series have been derived from a single observer, often with a unique telescope, in contrast with professional teams working in shifts and with a staff changing over the years (e.g., Clette et al, 2014;Carrasco et al, 2019).…”

Sunspot observations at Kawaguchi Science Museum: 1972 – 2013

“…In fact, data from individual sunspot observers have played significant roles on calibrations of the International Sunspot Number (version 2; hereafter SILSO SN V2) and comparison with other solar-activity indices, with significant homogeneity (Mathieu et al, 2019;Clette, 2021). Recent efforts have examined and described some cases of individual sunspot observers (Carrasco et al, 2019;Clette et al, 2014;Hayakawa et al, 2020;Vaquero et al, 2016), whereas further available records have to be analysed in this context.…”