Octans

Octans

Constellation
List of stars in Octans
Abbreviation	Oct
Genitive	Octantis
Pronunciation	/ˈɒktænz/, genitive /ɒkˈtæntɨs/
Symbolism	the Octant
Right ascension	22 h
Declination	−90°
Quadrant	SQ4
Area	291 sq. deg. (50th)
Main stars	3
Bayer/Flamsteed stars	27
Stars with planets	2
Stars brighter than 3.00m	0
Stars within 10.00 pc (32.62 ly)	1
Brightest star	ν Oct (3.73m)
Nearest star	LHS 531 (28.11 ly, 8.62 pc)
Messier objects	none
Meteor showers	none
Bordering constellations	Tucana Indus Pavo Apus Chamaeleon Mensa Hydrus
Visible at latitudes between +0° and −90°. Best visible at 21:00 (9 p.m.) during the month of October. Circumpolar.

Octans ( /ˈɒktænz/) is a faint constellation the southern sky. Its name is Latin for the eighth part of a circle, but it is named after the octant, a navigational instrument. The constellation was devised by Nicolas Louis de Lacaille in the eighteenth century.

Octans is notable as the location of the south celestial pole. Unlike the north pole, it has no bright pole star: Sigma Octantis (σ Oct) is a naked-eye star very close to the pole, but it is so faint (mag. 5.6) that it is practically useless for navigation purposes. Conviently for navigators, the constellation Crux, the Southern Cross, points toward the pole.

The constellation is circumpolar to the south celestial pole, so it can be seen in Southern Hemisphere skies during the evening in any month of the year. The Right Ascension and month of best visibility given are for the three brightest stars, which are at their highest in the sky during the evening in November.

Octans as the name

USS Octans (AF-26) was once a United States Navy ship.

References

• Ian Ridpath and Wil Tirion (2007). Stars and Planets Guide, Collins, London. ISBN 978-0007251209. Princeton University Press, Princeton. ISBN 978-0691135564.

External links

• The Deep Photographic Guide to the Constellations: Octans
• Starry Night Photography : Octans