Thomas Cragg Proves to Be a Good Observer (Abstract)

Volume 43 number 2 (2015)

Rodney Howe

3343 Riva Ridge Drive, Fort Collins, CO 80526; ahowe@frii.com

Frédéric Clette

World Wide Data Center SILSO, Royal Observatory of Belgium, Av. Circulaire, 3-B-1180 Brussels, Belgium; frederic.clette@oma.be

Abstract

(Abstract only) Longtime AAVSO member and observer Thomas A. Cragg proves to be a good solar observer, good enough to be included in the club of 21 long-duration stations without major stability problems over the interval 1945–2015. However, his sunspot counts seem to make a slight downward jump in 1983, and there is a sharp decline in the last two years of his observing career (due to aging?). Cragg’s observations will be used for the equivalent comparison with the new reconstructed sunspot number that is produced from the 21 stations showing the same features in the past six solar cycles. This reconstructed number is fully independent from the original Zürich sunspot number. It actually confirms the corrections being applied to the original sunspot number series (a more simple approach simply multiplying the original series by the correction factor established for the Locarno Observatory’s drift), as published in the 2014 paper by Frédéric Clette et al. (Space Sci. Rev., 186, 1–4, pp. 35–103).