From Halopedia, the Halo wiki
The Procyon system is a planetary system. Arcadia, a human Outer Colony world is located in this system. Procyon is orbited by at least four planets. It is situated five days Slipspace travel from the Epsilon Indi system.
In 2429, the fourth planet orbiting Procyon, Arcadia, was colonized by the Unified Earth Government, becoming a human colony known for its recreational amenities. Arcadia was invaded by the Covenant in 2531. The system's defense fleet engaged the Covenant ships, suffering heavy casualties. However, the Covenant left the system soon after without glassing the planet. A small number of human colonists remained on the planet in the town of Abaskun. It would remain a mostly lawless region, but continued to supply the UNSC with food. The Covenant would return to Arcadia later in 2549, glassing it.
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