Which constellation is named after a compass (drawing tool)?

The constellation named after a compass used for drawing circles is Circinus. Its name is Latin for a drafting compass, the hinged instrument used to construct circles and measure distances on diagrams.

Nicolas-Louis de Lacaille introduced Circinus in 1756 under the French name le Compas, meaning “the Compass.” He depicted it as a pair of dividing compasses on his chart of the southern sky. In 1763, the name was Latinized to Circinus, which became the official form used by astronomers.

Circinus is a small, faint constellation in the Southern Celestial Hemisphere near Alpha and Beta Centauri. It borders Centaurus, Musca, Apus, Triangulum Australe, Norma, and Lupus. Its brightest star, Alpha Circini, has an apparent magnitude of about 3.2 and is a rapidly oscillating chemically peculiar star.

The key distinction is between Circinus and Pyxis. Circinus represents a mathematical or drawing compass; Pyxis represents a mariner's compass used for navigation. Circinus is also part of Lacaille's group of tool-themed constellations, alongside Norma and the surveyor's level represented by Triangulum Australe.