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 Tyranids, to whose aid the Order of the Ebon Chalice came
An Imperial world invaded by the Tyranids. The Sisters of Battle of the Order of the Ebon Chalice came to its aid, but whether they saved it is not known. It is named once, in Salamanders: Rebirth (Chapter 21), and nothing else about it is published.
Era Indomituspost-Rift
[RECORD LOST]
No record for this location in Era Indomitus.
Position
Map frame: 948.8, 491.3 in the archive's 0–1000 disk space (core at 500, 500).
Distance from the core: 449 units ≈ 47.8k light years, east of the galactic core.
Height above the disk plane: -9.6 units — invented thin-disk jitter, deterministic per record. No published source gives any location a z coordinate.
System: Gethseda 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.
settinghigh
wh40k.lexicanum.com/wiki/Gethseda Lexicanum (read directly in a browser, 2026-10-05): 'Gethseda is an Imperium world that was invaded by Tyranids. The Sisters of Battle from the Order of the Ebon Chalice came to Gethseda's aid, though it is not known if they were able to save the world', sole source Rebirth (Novel), Chapter 21; Lexicanum Planets_(List): 'Gethseda ... Rebirth (Novel), Chapter 21'. MENTIONED, not visited: no page puts any scene there. NAME-COLLISION CHECK: no index record uses the id or label; Lexicanum has one Gethseda article.
typehigh
'planet': 'an Imperium world' (Lexicanum Gethseda).
classlow
editorial, NOT a citation: 'temperate', this dataset's neutral default for an inhabited world (as for Gabal, Aurelius and Brimlock), because no page gives a terrain, climate or colour word for Gethseda. Lexicanum's infobox Class is 'Unknown'. A Tyranid invasion is an event, not a surface. Repaint if a permitted source describes it.
segmentumhigh
null, stated rather than guessed: Lexicanum's infobox gives Segmentum, Sector, Subsector and System as 'Unknown'.
gposlow
inferred: named in the novel (Lexicanum Gethseda, Chapter 21) and unplaced anywhere, with no segmentum, sector, subsector, bearing or theatre published. Unsurveyed rim (rim_xy('gethseda') = [948.8, 491.3], r = 448.9 of the 470-unit disk, outside every stylised segmentum polygon; the function evaluated on its own; build_locations.py not run), no positional information. Z -9.6 is the zPolicy value (compute-z.mjs gethseda 948.8 491.3).
systemIdlow
'gethseda', named for the world because no system is published. no-system-survey: canon enumerates nothing about the system, so no systems/gethseda.json is authored.
eraslow
m41 only, and the date is the book's, not the world's: no page dates the Tyranid invasion or the Order's campaign there; it is named in a novel set in 980.M41. Allegiance 'contested' because the outcome is unknown (Lexicanum Gethseda). NEEDS CHECKING against the novel.