Norma is a small constellation in the Southern Celestial Hemisphere between Ara and Lupus, one of twelve drawn up in the 18th century by French astronomer Nicolas-Louis de Lacaille and one of several depicting scientific instruments.

Norma was introduced in 1751–52 by Nicolas-Louis de Lacaille with the French name l’Équerre et la Règle, "the Square and Rule",[2][3] after he had observed and catalogued 10,000 southern stars during a two-year stay at the Cape of Good Hope.

[2] Norma is bordered by Scorpius to the north, Lupus to the northwest, Circinus to the west, Triangulum Australe to the south and Ara to the east.

[8] The official constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930, are defined by a polygon of ten segments.

[b] Lacaille charted and designated ten stars with the Bayer designations Alpha through to Mu in 1756, however his Alpha Normae was transferred into Scorpius and left unnamed by Francis Baily, before being named N Scorpii by Benjamin Apthorp Gould, who felt its brightness warranted recognition.

Though Beta Normae was depicted on his star chart, it was inadvertently left out of Lacaille's 1763 catalogue, was likewise transferred to Scorpio by Baily and named H Scorpii by Gould.

Located 129 ± 1 light-years away from Earth,[12] Gamma2 Normae is a yellow giant of spectral type G8III around 2 to 2.5 times as massive as the Sun.

It also is half of a close optical double, with a magnitude 10 companion star related by line of sight only.

[12] Epsilon Normae is a spectroscopic binary, with two blue-white main sequence stars of almost equal mass and spectral type (B3V) orbiting each other every 3.26 days.

[14] The system is 530 ± 20 light-years distant from Earth,[12] Eta Normae is a yellow giant of spectral type G8III with an apparent magnitude of 4.65.

[17] Mu Normae is a remote blue supergiant of spectral type O9.7Iab,[18] one of the most luminous stars known, but is partially obscured by distance and cosmic dust.

A binary, it has a 2.4 solar mass (M☉) companion that is a blue-white main sequence star of spectral type B9.5V.

[24] A binary system composed of two wolf-rayet stars, colloquially called Apep, has been identified as a possible progenitor of a long gamma-ray burst.

[26] Norma hosts two faint R Coronae Borealis variable stars of magnitude 10—RT Normae and RZ Normae—rare degenerate stars thought to have formed from the merger of two white dwarfs that fade by several magnitudes periodically as they eject large amounts of carbon dust.

[27] A faint object of magnitude 16, QV Normae is a high mass X-ray binary star system 15,000–20,000 light-years distant from Earth.

Slightly larger and hotter than the Sun, it was found to have a roughly Jupiter-size planet with an orbital period of 2.8 years.

[40] Located 0.4° north of Kappa Normae is NGC 6067, which has an integrated magnitude of 5.6 though it is indistinct as it lies in a rich star field.

Mz 1 is a bipolar planetary nebula, thought to be an hourglass shape tilted at an angle to observers on Earth, some 3500 light-years distant.

[44] Mz 3—known as the Ant Nebula as it resembles an ant—has a complex appearance, with at least four outflow jets and two large lobes visible.