Astronomy and Astrophysics – Astrophysics
Scientific paper
Jul 1987
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1987a%26as...70...83w&link_type=abstract
Astronomy and Astrophysics Supplement Series (ISSN 0365-0138), vol. 70, no. 1, July 1987, p. 83-94.
Astronomy and Astrophysics
Astrophysics
39
Astronomical Catalogs, Solar Cycles, Sunspots, Visual Observation
Scientific paper
We have compiled a new catalogue of sunspot observations covering the period 165 BC to AD 1684 by updating and merging previously published catalogues and by adding a substantial amount of new data. The catalogue is in machine-readable form, the total number of entries being 235. Epoch analyses of the data have been made with regard to (a) the usefulness of naked-eye observable sunspots as tracers of the maximum epochs, and (b) the long-term phase behaviour of the sunspot cycle. The average period of the sunspot cycle is 11.116 ± 0.007 years, with individual periods ranging from 7.5 to 14.5 years (70% are between 9.9 and 12.3 years). Gaps (or scarcities of observations) are obvious between AD 600 and AD 800 (Medieval Minimum) and AD 1400-1500 (Sporer Minimum), but not during 1640-1715 (Maunder Minimum). A useful numerical approximation for the maximum epochs is: Year (Max.) = 4.0 + 11.116 N, where N is an arbitrary cycle number (N = 178 for the maximum of 1980/81).
Wittmann Axel D.
Xu Zhen-Tao
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