Properties of solar activity in the Dalton minimum

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The precise knowledge of the variability of the solar activity cycle is essential for the understanding of the generation of large-scale magnetic fields in the Sun. Apart from the well studied Maunder minimum in the second half of the 17th century with very few sunspots for several decades, the Dalton minimum around 1800 is not investigated well. With the original sunspot measurements of Copenhagen Observatory and the transit observations by Honoré Flaugergues, the proposal aims to obtain a large number of new sunspot positions and areas, sunspot group tilt angles and polarity separations for the time around the Dalton minimum. The positions will also allow us to determine the differential rotation of the Sun just before the Dalton minimum. The period is interesting for a comparison with the present low cycle 24 and the future development of solar activity.