Name a Star in the Circinus Constellation

The Circinus has only 5 connecting stars in its asterism. Three brighter stars create a slender triangle in the sky and two fainter stars are located on the longer sides of the shape. This far southern constellation is quite small, ranking 85 of the 88 recognized constellations!  It can be located throughout the northern hemisphere and only as far north South Florida, Egypt or Myanmar. Circinus is remarkable for containing two stars with known exoplanets and hosts a meteor shower each June, the Alpha Circinids, which was discovered in 1977.  

There are several Deep Sky Objects associated with this constellation. These include the famous Circinus Galaxy, the X-ray source Circinus X-1, and the pulsar PSR B1509-58. The open clusters NGC 5823 and NGC 5715, and the planetary nebula NGC 5315 are also located in the Circinus constellation. 

Symbol: Cir 

Right Ascension: 03:00 

Declination: -62 

Diameter (°): 7 

Area (square °): 93 

Opposition: May 08 

Size Rank: 85th 

Brightness Rank: 74th 

Genitive: Circini 

Major Stars in Circinus 

α Circini (Alpha Circini) 

β Circini (Beta Circini) 

γ Circini (Gamma Circini) 

ε Circini (Epsilon Circini)  

θ Circini (Theta Circini) 

HD 129445 includes planet “HD 129445 b” discovered in 2011 

HD 134060 includes two planets discovered in 2010 

Deep Sky Objects in Circinus 

Circinus Galaxy  

Circinus X-1 – an X-ray double star discovered in 1969 

NGC 5315  

NGC 5823  

NGC 5715  

Pismis 20  

PSR B1509-58 – a quickly moving pulsar with a spin-rate of over 6 times per second. Some observers claim to see the image of a hand or a face. 

History of the Constellation Circinus 

Because it is located in the far southern sky this constellation was not visible to most early Greek navigators. Therefore, the stars in the area of Circinus were not part of the Ancient Greek Mythology. Instead, this constellation was named for the Drafting Compass. It was catalogued in the 18th century by French astronomer Abbé Nicolas Louis de Lacaille. His work, Coelum Australe Stelliferum, was published in 1763 after his death.  Lacaille gave the asterisms he observed and catalogued from the Cape of Good Hope in South Africa the names of scientific and artistic objects of his day. The original French name for the constellation is le Compas. Unlike Pyxis, the Mariner’s compass, the drafting compass is used to create precise circular shapes. 

Lacaille named three of the constellations for drafting tools. These also included Norma, the Ruler or square and Triangulum Australe, the southern surveyor’s level. As an astronomer, mathematician, and geodesist (one who studies the shape of the Earth) these tools would have been essential to his studies.  Lacaille is credited with naming 14 constellations. He traveled to South Africa primarily to study the distance and positions of the planets using trigonometry along the longest possible baseline. With the support of several benefactors the observatory on the Shore of Table Bay was constructed from which he observed nearly 10,000 southern stars. Constellations named by Lacaille during that time include Antilia, Caelum, Circinus, Fornax, Horologium, Mensa, Microscopium, Norma, Octans, Pictor, Reticulum, Sculptor, and Telescopium.