Giovanni Domenico Cassini
The Maunder Minimum occurred between 1645 and 1715 when very few sunspots were observed. That was not because of a lack of observations, as during the 17th century, Giovanni Domenico Cassini carried out a systematic program of solar observations at the Observatoire de Paris, thanks to the astronomers Jean Picard and Philippe de La Hire. Johannes Hevelius also performed observations on his own. Here is the total of sunspots recorded, by example, in the decennial years (omitting Wolf numbers):