Pronunciation:

 (OK-tanz)

Abbreviation:

 Oct

  Genitive:

 Octantis 

Right Ascension:

 22 hours

  Declination:

 -85 degrees

Area in Square Degrees:

 291

Crosses Meridian:

 9 PM, September 20

Visible Between Latitudes:

 -5 and -90 degrees

The constellation Octans, the octant, is located in the southern hemisphere of the sky. It is only visible at latitudes south of the equator. It is a circumpolar and is visible all night long. It is a small constellation with a total area of only 291 square degrees. This ranks it 50th in size among the 88 constellations in the night sky. Octans is bordered by the constellations Apus, Chamaeleon, Hydrus, Indus, Mensa, Pavo and Tucana. It also contains the South Celestial Pole.

There is no mythology associated with the constellation Octans. It is one of 14 constellations named by the French astronomer Nicolas Louis de Lacaille in 1752 after his trip to the Cape of Good Hope to study the southern night sky. It is named after the octant, a navigational tool that was the precursor to the modern day sextant. Octans was originally named de Reflexion", which was French for “the reflecting octant”. It eventually became known as Octans Hadleianus after John Gadkey, the English mathematician who invented the octant in 1730.

The constellation Octans showing common points of interest
The constellation Octans showing common
points of interest. © Sea and Sky
Octans constellation map
Octans constellation map.
© Torsten Bronger CC BY-SA 3.0
Object
Designation
Name / Meaning
Object Type
V Mag
1 2 3 4 5 6
Nu Octantis
Beta Octantis
Delta Octantis
Theta Octantis
Epsilon Octantis
Polaris Australis
N/A
N/A
N/A
N/A
N/A
"Southern Pole"
Orange Giant Star
White Subgiant Star
Orange Giant Star
Orange Giant Star
Red Giant Star
Yellow-White Giant Star
3.76
4.14
4.31
4.78
5.16
5.45

Octans contains only faint stars and no Messier objects. The most famous star in this constellation is Polaris Australis, the southern pole star. It is the star closest to the south celestial pole. In spite of its significance, the star is extremely dim. Its visual magnitude is only 5.45, which makes it far too dim to be used for navigation. The brightest star in this constellation is Nu Octantis with a visual magnitude of only 3.76. It is an orange giant star located about 69 light years from Earth. The second brightest star us Beta Octantis with a magnitude of only 4.14. It is a white subgiant star that lies 140 light years away. Octans contains no notable deep-sky objects.