Sigma Octanus system

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Sigma Octanus
Stellar overview

Orbiting planets:

At least 4

Societal overview


Unified Earth Government


The Sigma Octanus system is a planetary system with at least four planets orbiting a binary star located in FLEETCOM Sector Three.[1] The system is home to the UEG colony world of Sigma Octanus IV, which had a population of over 17 million people prior to the Battle of Sigma Octanus IV.[2]

During the Battle of Sigma Octanus IV, Captain Jacob Keyes performed the famous Keyes Loop in the system.[3] In addition, John-117 and the Blue Team found a strange Forerunner artifact in Côte d'Azur Museum of Natural History on Sigma Octanus IV while the Covenant tried to retrieve it.[4] The system remained under UNSC control after the battle which ended in a rare UNSC victory.


  • While there is no actual star with the designation "Sigma Octanus", there is one named "Sigma Octantis" located 270 light years from the Sol system. However, it is unlikely to be the same system for a number of reasons: The real-world Sigma Octantis is classified as an F0 III-type giant instead of a binary star. In addition, such distance would make Sigma Octanus the astronomically farthest known UEG colony, significantly farther than the Outer Colony system 23 Librae which was considered to be "behind enemy lines" by 2535. Furthermore, UNSC Iroquois traveled from the system to Reach in less than a month. Traveling over 250 light years in such timeframe would be difficult with war-period human slipspace velocities.
  • Although the system contains a binary star,[1] one of the stars (likely the primary) is apparently known as Sigma Octanus as it is stated that "light from Sigma Octanus" reflected off the debris of the battle in the system.[5]

List of appearances[edit]


  1. ^ a b Halo: The Fall of Reach, page 211 (2001); page 242 (2010)
  2. ^ Halo: The Fall of Reach, page 144
  3. ^ Halo: The Fall of Reach, pages 144-146
  4. ^ Halo: The Fall of Reach, page 208
  5. ^ Halo: The Fall of Reach, page 215 (2001)