This archive tracks four layers. A record present in 1 of them (M41) 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
contested
Imperial world invaded by Chaos, 13th Black Crusade
An Imperial world invaded during the 13th Black Crusade by a daemonic army under Duke Venalitor, champion of Khorne, which makes landfall on the southern polar cap and overwhelms the Hathran Armoured Cavalry holding the ice-bound pass of the Reliquus Mountains. Justicar Alaric's Grey Knights fight to stop the daemonic host taking the planet. Hammer of Daemons opens here.
Era Indomituspost-Rift
[RECORD LOST]
No record for this location in Era Indomitus.
Position
Map frame: 846.3, 759 in the archive's 0–1000 disk space (core at 500, 500).
Distance from the core: 432 units ≈ 46k light years, south-east of the galactic core.
Height above the disk plane: -7.7 units — invented thin-disk jitter, deterministic per record. No published source gives any location a z coordinate.
System: Sarthis Majoris System
Books set here
1 title in the reading tracker touches this record. Titles link out to the tracker.
Every fact in this record, and where it came from. Editorial derivations say so.
identitymedium
wh40k.lexicanum.com/wiki/Alaric No Lexicanum article exists for Sarthis Majoris (checked 2026-10-03). It is named on three pages that cite Hammer of Daemons, all read directly in a browser on 2026-10-03: ('Alaric and his squad are on the planet Sarthis Majoris attempting to stop a daemonic army from taking over the planet'), https://wh40k.lexicanum.com/wiki/Venalitor (ch. 16: 'led a Chaos invasion on the planet Sarthis Majoris and made landfall on the southern polar cap ... overwhelmed the Hathran Armoured Calvary sent to defend the ice-bound pass of the Reliqus Mountains') and https://wh40k.lexicanum.com/wiki/Nyxos ('Sarthis Marjoris', sic). NAME-COLLISION CHECK: no index record uses the id or label.
book-joinhigh
VISITED for Hammer of Daemons (grey-knights::gk-main::2.6): the battle in which Alaric challenges Venalitor and is captured with Haulvarn (Lexicanum Alaric 'Sarthis Majoris'; Venalitor ch. 16).
segmentummedium
null: no permitted source names a segmentum, sector or neighbour for Sarthis Majoris. That it was invaded during the 13th Black Crusade does not locate it: Venalitor's forces raid other worlds from Drakaasi, and nothing says how far.
classlow
'ice', chosen by what the book shows: the only terrain canon gives is the 'southern polar cap' where Venalitor lands and 'the ice-bound pass of the Reliqus Mountains' (Lexicanum Venalitor). That is where the world is seen; nothing describes the rest of the planet, so the class paints the scene, not a claim about the whole world.
gposlow
inferred: the book names the world but no permitted source locates it, so the record claims no segmentum and sits on the unsurveyed rim at the generator's rim_xy('sarthis-majoris') = [846.3, 759.0] (ported function, checked against aurelius = [120.7, 262.4]; build_locations.py itself was not run). The position carries no information and must not be read as one. Z -7.7 is the zPolicy value (compute-z.mjs sarthis-majoris 846.3 759.0).
no-system-surveymedium
No systems/sarthis-majoris.json: canon names no star, no sibling and no body count (the 'Majoris' suffix implies a sibling, but none is named), so a survey would be invented.
erasmedium
m41 only, the novel's era (999.M41, the 13th Black Crusade). Allegiance 'contested': an Imperial world under Chaos invasion. What becomes of it after Alaric's capture is not published.