Two debatable cases for the reconstruction of the solar activity around the Maunder Minimum: Malapert and Derham

We perform case studies of the sunspot observations by Charles Malapert and William Derham from the point of view of the reconstruction of the solar activity. They made sunspot observations prior and after the deep Maunder Minimum, respectively, being two of the most active sunspot observers of their time. The currently available sunspot group data bases assign one sunspot group for most of observations by Malapert and Derham. However, with documental evidence, we attest that these observers would have sometimes recorded several sunspot groups as only one representative group. Therefore, we conclude that their sunspot group counting should be used with caution for the reconstruction of the solar activity level around the Maunder Minimum.