Tycho's mural quadrant picture. Mural depicting Danish astronomer Tycho Brahe (1546-1601, centre) in his observatory on the island of Hveen (now Ven, Sweden). Tycho was the last of the naked eye astronomers, improving almost every astronomical observation. In lower frame, observatory staff are measuring the position of a star. At far right, a man is viewing a star through a sliding frame mounted on the brass quadrant. He is viewing the star through the small window at upper left. A man is recording the time of the sighting (lower right) while yet another (lower left) takes a written record of the event. In the background, three other floors of the observatory are seen.