Circinus constellation is located in the southern sky. Its name means “the compass” in Latin, referring to the tool for drawing circles.
Circinus was created and first catalogued by the French astronomer Nicolas Louis de Lacaille in the 18th century. Lacaille created the constellation to bridge the void between Triangulum Australe and the stars marking Centaurus‘s forefeet.
Circinus contains several notable deep sky objects, including the Circinus Galaxy, the X-ray source Circinus X-1, the pulsar PSR B1509-58, the open clusters NGC 5823 and NGC 5715, and the planetary nebula NGC 5315.
FACTS, LOCATION & MAP
Circinus is the fourth smallest constellation in the sky, 85th in size, occupying an area of only 93 square degrees. It lies in the third quadrant of the southern hemisphere (SQ3) and can be seen at latitudes between +30° and -90°.
The neighboring constellations are Apus, Centaurus, Lupus, Musca, Norma, and Triangulum Australe.
Circinus does not have any stars brighter than magnitude 3.00 or located within 10 parsecs (32.6 light years) of Earth. The brightest star in the constellation is Alpha Circini, which is also the nearest star in Circinus, located at a distance of 53.50 light years from Earth.
Circinus belongs to the Lacaille family of constellations, along with Antlia, Caelum, Fornax, Horologium, Mensa, Microscopium, Norma, Octans, Pictor, Reticulum, Sculptor, and Telescopium.
Circinus has two stars with known exoplanets, HD 134060 (spectral class G0VFe+0.4) and HD 129445 (G6V). HD 134060 has two planets in its orbit, both discovered in 2011, and HD 129445 has one, a Jupiter-like planet discovered in 2010. Circinus does not contain any Messier objects. It is associated with a meteor shower that peaks on June 4, the Alpha Circinids (ACI), first observed in 1977.
STORY
There are no myths associated with Circinus. The constellation was named after the drafting tool used for drawing circles (not after a mariner’s compass, which is represented by the constellation Pyxis).
It is depicted as a pair of dividing compasses used by draughtsmen to measure distances.
Lacaille originally named the constellation le Compas and placed it next to Triangulum Australe, which he depicted as a surveyor’s level, to fill the void between several existing constellations in the south.
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