Cyclic behaviour of sunspot activity during the Maunder minimum

We study the behaviour of sunspot activity in 1610-1750, i.e. just prior to , during and slightly after the Maunder minimum, using the new series of gr oup sunspot numbers (Hoyt & Schatten 1998). We apply the delayed component technique and show that, while the transition from the normal cyclic evolut ion to the minimum was very abrupt, the recovery from the minimum was gradu al, proceeding through a tiny but very regular cycle in 1700-1712 and a tra nsition period with a phase catastrophe in 1712-1720. Exploiting the good c overage of the Maunder minimum by daily solar observations, we show that th e sunspot ocurrence is concentrated, with a high statistical significance, to two intervals around 1658 and 1680. Together with the last sunspot maxim um before the Maunder minimum in 1639/1640, and the maximum in 1705, this i mplies a significant, approximately 22-year periodicity in sunspot activity during the Maunder minimum.