This archive tracks four layers. A record present in 4 of them (HH, AoI, M41, IND) is silent in the rest, and says so.
The Horus HeresyM30–M31
imperium
Homeworld of Ferrus Manus and the X Legion
A tectonic wreck of a world where continents move fast enough to kill, organised into clans that judge a person by what they have replaced. Ferrus Manus was found on it and the Legion never stopped being Medusan.
Age of the ImperiumM32–M40
imperium
Iron Hands homeworld
Clan-companies more than a Chapter, each keeping its own fleet and its own grudge.
The 41st Millenniumpre-Rift
imperium
Iron Hands homeworld
Still shifting, still lethal, still producing recruits who regard their own flesh as the weakest part of the equipment.
Era Indomituspost-Rift
imperium
Iron Hands homeworld
Close enough to the Eye that the Rift's opening was felt as weather.
Position
Map frame: 146, 262 in the archive's 0–1000 disk space (core at 500, 500).
Distance from the core: 427 units ≈ 45.4k light years, north-west of the galactic core.
Height above the disk plane: -10.7 units — invented thin-disk jitter, deterministic per record. No published source gives any location a z coordinate.
System: Sthenelus System
Books set here
2 titles in the reading tracker touch this record, 1 of them as a primary location. Titles link out to the tracker.
wh40k.lexicanum.com/wiki/Medusa_IV infobox Class = Adeptus Astartes Homeworld, Waste World, unofficially a Death World. https://wh40k.lexicanum.com/wiki/Medusa_(Planet): "a harsh realm of perpetual gloom", "a dark and polluted sky", geology "highly unstable, with earthquakes, electrical storms, and volcanic eruptions constantly creating and destroying mountain ranges and seas". RENDERED forge, NOT death (2026-09-01), for the same reason as nocturne: the death palette is a jungle and this world is volcanic waste
gposmedium
wh40k.lexicanum.com/wiki/Medusa_IV derived: — 'located extremely close to the Eye of Terror'. Placed just outside our Eye feature's radius, west of it, inside the Obscurus boundary
labelhigh
Lexicanum titles the article 'Medusa IV' and notes it is 'commonly referred to as Medusa'. The common form is used as the label