The constellation named after the carpenter's square is Norma. Its Latin name refers to a right angle and is commonly associated with a set square, rule, or carpenter's square.
French astronomer Nicolas-Louis de Lacaille introduced Norma in 1751–52 after surveying the southern skies from the Cape of Good Hope. He originally called it l'Équerre et la Règle, meaning “the Square and Rule,” and included it among a group of constellations representing instruments of science and craftsmanship.
Norma is a small southern constellation between Scorpius, Lupus, Circinus, Triangulum Australe, and Ara. It is not especially bright: its brightest star, Gamma2 Normae, has an apparent magnitude of about 4.0. The Milky Way crosses Norma, giving it several open star clusters and a rich background of faint stars.
A common mix-up is Circinus, which represents a drawing compass, while Norma represents the square or angle-measuring tool. Norma is one of the 88 modern constellations recognized by the International Astronomical Union.