This archive tracks four layers. A record present in 2 of them (M41, IND) is silent in the rest, and says so.
The Horus HeresyM30–M31
[RECORD LOST]
No record for this location in The Horus Heresy.
Age of the ImperiumM32–M40
[RECORD LOST]
No record for this location in Age of the Imperium.
The 41st Millenniumpre-Rift
imperium
Hive world, and what was left of it
A world that mattered to the Imperium until the Thousand Sons decided it mattered to them. The past tense in every published sentence about it is the summary.
Era Indomituspost-Rift
unknown
[RECORD LOST]
[RECORD LOST]
Nothing survives in the archive for Era Indomitus.
Position
Map frame: 798, 187.2 in the archive's 0–1000 disk space (core at 500, 500).
Distance from the core: 432 units ≈ 46k light years, north-east of the galactic core.
Height above the disk plane: 3.7 units — invented thin-disk jitter, deterministic per record. No published source gives any location a z coordinate.
System: Aerius System
Books set here
1 title in the reading tracker touches this record, 1 of them as a primary location. Titles link out to the tracker.
Every fact in this record, and where it came from. Editorial derivations say so.
classhigh
wh40k.lexicanum.com/wiki/Aerius infobox Class = Former Hive World; lead — 'Aerius was a Hive World of great importance to the Imperium'; no segmentum, sector or system
gposlow
inferred: no published segmentum, sector, subsector or system, and no article places the world against a neighbour or a theatre. No segmentum is claimed; unsurveyed rim, no positional information.