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.
Position in this era: [RECORD LOST].
Age of the ImperiumM32–M40
[RECORD LOST]
No record for this location in Age of the Imperium.
Position in this era: [RECORD LOST].
The 41st Millenniumpre-Rift
contested
Ultramarines star fort, prison of a Daemon Prince; taken by the Iron Warriors in 999.M41
A Ramilies-class star fort in Ultramarines service, by Moriana's account a weapons platform to rival the Blackstone Fortresses. After 935.M41 it was a wandering prison guarded by half the Fifth Company, until Warsmith Honsou stormed it on the eve of the invasion of Ultramar.
Position: Veridian System (Calth) In the outer orbit of Calth when M'kar's daemonic horde seized it in 935.M41 and Marneus Calgar boarded it; afterwards sent wandering in and out of the Warp as M'kar's prison. Canon never says where on that random course Honsou's army found and took it in Iron Warrior, so the novella is drawn at the fort's last charted station rather than at an invented one
Position: Talassar System (Talassar) Honsou's headquarters for the Bloodborn invasion of Ultramar: first seen over Tarentus, then in orbit of Talassar, where it was destroyed by the battle barges Octavius and Severian and fell into the ocean Cited in The Chapter's Due
Era Indomituspost-Rift
[RECORD LOST]
No record for this location in Era Indomitus.
Position in this era: [RECORD LOST].
Position
A mobile record: it carries a position timeline rather than a fixed point. The archive places it in 1 of the four eras (M41); each era section above carries that era's entry.
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.
Every fact in this record, and where it came from. Editorial derivations say so.
labelhigh
wh40k.lexicanum.com/wiki/Indomitable 'This article is about the star fort. For other uses of Indomitable, see Indomitable (disambiguation)'. NAME COLLISION checked: the id carries -star-fort so a later ship or world called Indomitable gets its own record
classhigh
wh40k.lexicanum.com/wiki/Indomitable 'a Ramilies-class star fort, in the service of the Ultramarines'; https://wh40k.lexicanum.com/wiki/Ramilles_Class_Star-fort lists it among notable Ramilies star forts and (citing Iron Warrior ch. 2) describes them towed through the warp by up to six hundred tugs. A station, so it renders as a holo schematic, not a globe; archetype star-fort-ramilies is the same hull family as Watch Fortress Erioch
mobilehigh
wh40k.lexicanum.com/wiki/M%27kar citing Iron Warrior ch. 1: Calgar 'detailed half of the Ultramarines' Fifth Company to garrison the star fort and guide it on a constant, random journey in and out of the warp'. A star fort that moves between systems is a positions[] timeline, not a fixed gpos
positionsmedium
wh40k.lexicanum.com/wiki/Indomitable 'In 935.M41, a daemonic horde led by M'kar the Reborn took control of the Indomitable, located in the outer orbit of Calth' (Codex: Space Marines 5th ed. p. 40); 'first appeared in the skies above Tarentus' and 'By the time the Ultramarines responded, the fort was in orbit of Talassar' (The Chapter's Due chs. 1, 22); destroyed by the battle barges Octavius and Severian, 'its remains fell to Talassar and plunged into the ocean' (ch. 24). Where Honsou captured it (Iron Warrior) is unpublished: the first entry, the default for that book, is its last charted station at Calth and says so
eras.m41high
wh40k.lexicanum.com/wiki/Indomitable Moriana calls it 'a weapons platform to rival the Blackstone Fortresses seized during the Gothic War' (Iron Warrior ch. 1); 'Warsmith Honsou of the Iron Warriors learned of M'Kar's whereabouts, and captured the fort in a bloody siege, slaughtering its garrison' (Iron Warrior); invasion dated 999.M41 (Lexicanum Honsou, M'kar). Status names the capture without naming the prisoner's release, which is the novella's spoiler
no-system-surveyhigh
No systems/<id>.json: the Indomitable is a mobile station, not a system. It docks into veridia (Calth, which has a survey) and talassar by its positions[] timeline