There are 5 unique codex entries in the Achievement: Datacrons section on Ilum. They are accessible to all players regardless of class or faction.
Galactic History 83: The Republic Rebuilds | Coordinates: 925, 1076 | Location: Ilum: Eastern Ice Shelf
Galactic History 83: The Republic Rebuilds is obtained from interacting with the +4 Blue Mastery datacron.
Codex type: Achievement: Datacrons | Faction: Both | Class: All
Associated Achievement: Ilum Datacron Master
Galactic History 84: The G0-T0 Coup | Coordinates: 104, -78 | Location: Ilum: Eastern Ice Shelf
Galactic History 84: The G0-T0 Coup is obtained from interacting with the +4 Green Endurance datacron.
Codex type: Achievement: Datacrons | Faction: Both | Class: All
Associated Achievement: Ilum Datacron Master
Galactic History 85: The Purge of the Dark Council | Coordinates: 544, 544 | Location: Ilum: Eastern Ice Shelf
Galactic History 85: The Purge of the Dark Council is obtained from interacting with the Red Matrix Shard datacron.
Codex type: Achievement: Datacrons | Faction: Both | Class: All
Associated Achievement: Ilum Datacron Master
Galactic History 86: The Empire's Revenge | Coordinates: 312, -380 | Location: Ilum: Eastern Ice Shelf
Galactic History 86: The Empire's Revenge is obtained from interacting with the Yellow Matrix Shard datacron.
Codex type: Achievement: Datacrons | Faction: Both | Class: All
Associated Achievement: Ilum Datacron Master
Galactic History 87: A Wayward Apprentice | Coordinates: 304, -1570 | Location: Ilum: Eastern Ice Shelf
Galactic History 87: A Wayward Apprentice is obtained from interacting with the +4 Purple Mastery datacron.
Codex type: Achievement: Datacrons | Faction: Both | Class: All
Associated Achievement: Ilum Datacron Master