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A History of the Zurich and American Relative Sunspot Number Indices


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Casper H. Hossfield

P. O. Box 23, New Milford, NY 10959


Based on a paper presented at the 89th Annual Meeting of the AAVSO, October 28, 2000; revised July 2001


[Ed. note: We are sad to report that Casper Hossfield died on November 26, 2002, at the age of 84. Cap was an AAVSO member for 40 years. He was Chair of the Solar Division from 1963 to 1979, and was­-for the past 3 years­-the Editor of the Sudden Ionospheric Disturbances Supplement of the AAVSO Solar Bulletin. An obituary will appear in a future issue of this journal. At the time of his death Cap was preparing this article for publication in the AAVSO Journal. We publish it now as a tribute to his many years of service and dedication to the AAVSO.]


Abstract  I trace the 133-year history of the Zurich Relative Sunspot Number Index, RZ, from its beginning in 1848 through to 1981 when the index was terminated. I also trace the history of the American Relative Sunspot Number Index, RA, from when it was first set to the Zurich scale in 1944 through to the present.

Link to ADS abstract, article and citation information

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