New paper in A&A of interest to some Talkshop readers. The authors use drawings by Schwabe, from there estimate details about solar marks. Recently solar cycle 24 has been likened to solar cycle 7, adding interest
Sunspot areas and tilt angles for solar cycles 7–10
V. Senthamizh Pavai, R. Arlt, M. Dasi-Espuig, N.A. Krivova, and S. K. Solanki
A&A 584, A73 (2015)
Open access on registration
Fig.2. Example of the drawing style in the initial period of 1825-1830.
This full-disk drawing of 1827 June 13 shows large spots which com-
bine several umbrae and at least part of the penumbral area, as is re-
vealed by the detailed drawings.
I’m short on energy, above is brief and without much in the way of quotes. Any who look at the paper please add detail in comments.
Post by Tim