Constellation Octans (Octant)

Octans: IAU Constellation Map [150]


The constellation Octans is at the south celestial pole. But this is the only thing that distinguishes this inconspicuous, amorphous part of the sky. There is no counterpart to the northern pole star in the southern sky: the closest star that is just visible to the naked eye is σ Octantis (5.5 mag), which is about 1 degree away from the pole. The constellation area is 291 square degrees. [9, 15]

Stars with Proper Names [154]
σ Oct Polaris Australis
Data for constellation Octans [150]
IAU NameOctans
IAU GenitiveOctantis
IAU Abbr.Oct
English NameOctant
Season (47° N)Not visible
Right Ascension00h 00m 00s … 24h 00m 00s
Declination-90° 00' 00" … -74° 18' 14"
Area291 deg2
Neighbours (N↻)Ind, Pav, Aps, Cha, Men, Hyi, Tuc



The constellation is reminiscent of an angle measuring device that was invented by John Hadley in 1730 and used to measure the positions of the stars - a forerunner of the sextant. The original name of the constellation reminds of the inventor: Octans Hadleianus. Like the other technical and scientific equipment in the southern sky, it was introduced in the middle of the 17th century by the French Abbé Nicolas Louis de Lacaille. [7]


  • [7] «Der grosse Kosmos-Himmelsführer» von Ian Ridpath und Wil Tirion; Kosmos Verlag; ISBN 3-440-05787-9
  • [9] «Drehbare Sternkarte SIRIUS» von H. Suter-Haug; Hallwag-Verlag, Bern
  • [15] «Hartung's Astronomical Objects for Southern Telescopes» by David Malin and David J. Frew; Melbourne University Press 1995; ISBN 0-522-84553-3
  • [150] IAU: The Constellations, 11. Oktober 2020;
  • [154] Yale Bright Star Catalog, 15. Oktober 2020;