This engraving shows Danish astronomer, Tycho Brahe, in his observatory on the island of Hven. In the foreground, three apprentices are sighting and recording the movements of a celestial object using a large quadrant. This was one of seven engravings of the life and works of Brahe published in Blaeu's Atlas Major. This engraving is still part of a bi-folium with three pages of Spanish text.
References: cf. Kanas #8.15; cf. Whitfield #91.
Superb impression on a bright sheet with light dampstains along the edges, just entering image at top right.