Installation 03

Installation 03, also known as Eta Halo, is one of the seven rings in the Halo Array. It was originally part of a smaller array of six Halos with a diameter of 10,000 kilometers, as opposed to the 12 larger, 30,000-kilometer-wide Halo installations. Its monitor is 03-049 Abject Testament. It appears to have a red and cracked surface, indicating the presence of vast deserts, as well as what appears to be volcanic activity, the latter of which exists through clearly artificial means.

Forerunner-Flood war
As with the other seven Halo rings, Installation 03 was fired at the conclusion of the Forerunners' war with the Flood, killing all sentient life within its effective radius. Afterwards, it entered an inactive state along with the rest of the Array.

Human-Covenant War
On November 3, 2552 during the Battle of Installation 05, a signal was sent to this Halo from Installation 05, putting it on standby mode and preparing it to fire on demand. On December 11, 2552, the installation was still in standby mode and was about to be fired at the behest of the High Prophet of Truth, who had seized Installation 00's control room. However, the Array was deactivated by SPARTAN John-117 and the Hierarch was assassinated by Arbiter Thel 'Vadam before this could occur.

Post-war
The Office of Naval Intelligence discovered the installation's location some time after the Human-Covenant War had ended. Subsequently, the top-secret research station Ivanoff was built in the Halo's orbit, presumably with 049 Abject Testament's permission. In March 2553, Catherine Halsey was indefinitely detained here by Admiral Margaret Parangosky, as retribution for lying to her about the creation and deployment of flash clones during the SPARTAN-II program's early phases. The MJOLNIR/Pioneer variant first saw field use during the initial ground exploration of Installation 03. 049 Abject Tesrament apparently also allowed the humans to retreive and store the index for Halo 03, and other relics from the instalation, on the Ivanoff station.

At some point after being established, the scientists in the facility located the Forerunner weapon known as The Composer and data from an accident with it led to the Shield World known as Requiem. When The Didact was awakened, he traveled to Ivanoff in his ship Mantle's Approach and acquired the Composer using it to digitize Ivanoff's staff before jumping to Slipspace to travel to Earth to use the recovered weapon on humanity's homeworld.

List of appearances

 * Halo 2
 * Halo 3
 * Halo Legends
 * Origins
 * Halo: Glasslands
 * Halo: Combat Evolved Anniversary
 * Terminal
 * Halo 4