Installation 03

Installation 03, also known as Gamma Halo,  is one of the seven rings in the Halo Array. Its monitor is 049 Abject Testament. The ring appears to have a red and cracked surface, indicating the presence of vast deserts, as well as volcanic activity.

Unlike Installations 04 and 05, which orbit large gas giants, Installation 03 orbits a rocky planet, the face of which has been shattered as a result of a fairly recent impact event; the debris from the impact, still aglow as of 2557, has collected to form a dense asteroid field in orbit over the planet as well as the Halo.

Forerunner-Flood war
Shortly before the activation of the Halo Array at the end of the Forerunner-Flood war, the IsoDidact convened a meeting of the surviving Lifeworkers and the monitors who would serve as the rings' caretakers at Installation 00. 049 Abject Testament was designated as Gamma Halo's monitor and was given the Halo's activation index. Along with the other six rings, Installation 03 was fired, killing all sentient life within its effective radius. Afterwards, it entered an inactive state along with the rest of the Array.

Discovery
During the Battle of Tribute in August 2552, the freighter Floral Express fled the planet while carrying colonial refugees. Presumably following a random slipspace trajectory per the Cole Protocol, the ship arrived near Installation 03 on October 8th. Based on intelligence gleaned from the Battle of Installation 04, ONI teams had established and enacted neutralization protocols on Gamma Halo by October 25th.

Standby and deactivation
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
By March 2553, the top-secret research station Ivanoff had been built in Installation 03's orbit. That month, Dr. Catherine Halsey was indefinitely detained there by Admiral Margaret Parangosky, CINCONI, as retribution for lying to the latter 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.

The Composer
The ONI science teams retrieved various artifacts from the surface of Installation 03 and brought them on Ivanoff Station for study, including the installation's activation index and a Composer. An accident with the Composer killed the team researching the device; however, it provided coordinates which led the 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. However, SPARTAN-117 and Cortana followed the Didact into slipspace in an F-41 Broadsword in hopes of foiling his plan, ultimately defeating him.

List of appearances

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