Circinus appears just to the east of the foot of Centaurus. A line through Alpha and Beta Centauri points to Circinus. Because it is so far south, it is invisible to observers in most of the Northern Hemisphere.
History and Mythology
Circinus was introduced by Nicolas Louis de Lacaille in 1752. Because of Lacaille's desire to fill the entire southern sky with many scientific objects, he named this particular group in the sky as the Pair of Compasses.
Notable Objects
Circinus is a small, undistinguished constellation. It is the fourth smallest of the constellations, and it has no prominent stars. Directly south of Alpha Centauri is Alpha Circini, with a magnitude of 3.2. It is the only star brighter than 4th magnitude in this constellation.
Alpha Circini is an interesting double star with magnitudes of 3.2 and 8.6 and a separation of 15.7 arcseconds. Another double is Gamma Circini with magnitudes of 5.1 and 5.5.
NGC 5315 is a small planetary nebula with a bluish-green disc. NGC 5715 is a 10th magnitude open cluster in the northern part of Circinus. NGC 5823 is a small open cluster of about 9th magnitude.