Where is it mentioned? I've tried looking at the wiki and lexicanum, I even looked through my CSM codex and didn't find much.
Which one? The lexicanum and wiki both are severely lacking, and I don't imagine the csm codex mentioning much about navigation.
Chaotic ships in no way use the Astronomican, [...]
[...] and yet they still manage impressive jumps, even going in and out of the Eye of Terror, which is probably the most dangerous zone of "realspace" (if such a term can be applied to it), and in which the light of the Astronomican certainly doesn't shine. It's perfectly doable. Example: a Word Bearers armada jumping from the Eye directly to Ultramar, unnoticed before they arrive. Honsou does the same. The Eye and Ultramar are at opposite points of the galaxy.
The Astronomican is centered on Terra, shining to the edges of the galaxy. The Astronomican definitely shines throughout the Eye of Terror. The Eye of Terror is just a rift between realspace and The Immaterium, and as far as I know, there's absolutely no reason the Eye of Terror would somehow block the Light of the Astronomican.
I remember a short story about an Imperial ship being followed in the Warp by a chaotic ship, to which the ship's captain remarks it's theoretically impossible. Imperials, deprived of the Astronomican, would be lost, yes. Heretics have since long developped methods that simply do not require it at all. You can have your interpretation of the fluff, sure, but most of the written material makes me pretty sure that what I say is "canon".
If you know of the way the forces of Chaos navigates in general, you've got me bested. By all means, explain how they do it, or cite a source.
And remember: we're not talking about rational people here. I don't picture most Heretics willingly guiding themselves with the Corpse-Emperor's nightstand lamp.
And why wouldn't they? Pride? The Astronomican is hardly a "nightstand lamp" - it's an enormous psychic beacon that is at a fixed location in both the Materium and the Immaterium - something that, as far as I know, doesn't otherwise exist.
While I do not contend that there are other ways to navigate the warp, because there certainly are
several ways, all which are incredibly taxing or otherwise inefficient, to say that the forces of chaos have "since long developped methods" to navigate the Warp is unfounded hogwash.
The more powerful servants of Chaos (CSM, Daemon Princes, etc) surely stick to techno-arcane sorcery and the favours of their dark masters, of this I am sure and fully agree with you on. But not only is only a comparative minuscule amount of humanity truly dedicated to the dark gods, but even the vast majority of those, the Lost and the Damned, would not be directly favoured by their black patrons, nor have access to means of travel aside from what they had when they left the Imperium, but more importantly; they have no cause to abandon this form of transportation for as long as the Astronomican remains, nor direct access to the resources needed to make the transition(s) needed once it's not.
-I have no citation for that, true. What I do have is a number of examples of my thesis, and none of Heretics using the Astronomican. Not to say that doesn't happen (I went a bit overboard on that one, granted), but given the sparse nature of evidence when it comes to 40k fluff, I call that (circumstantial if you wish) evidence.
-It does, as seen in the novel Angel Exterminatus. The fleets of Perturabo and Fulgrim have to be guided in by Dark Eldar.
-What I have are examples. Octavia and Ruven in the Night Lords trilogy (one cannot see the beacon and relies on sorcerous powers, the other is a Navigator but learns to do without it); the Word Bearers fleet in the Word Bearers trilogy (navigators are mentionned, but again, the light of the Astronomican is conspicuously absent from any description); Honsou attacks Ultramar and appears suddenly in system within range of the orbital defenses (which no navigator can do, at least not that purposefully); in Execution Hour, a daemonhost guides a ship more easily and accurately than a navigator would; Typhus guiding the Death Guard to Nurgle's loving bosom; etc.. I have other examples of this, but this is already plenty.
-Pride? No. Hatred? **** yes. Hatred is the most powerful motivator known to man, and I'm not even considering Heretics here, just regular human beings.
10000 years is plenty enough to be considered "since long". Unfounded hogwash? See above. And they seem more precise to me, since Chaos fleets seem to have way more accuracy in where they strike compared to the numerous accounts of lost Imperial fleets...
And those Lost and Damned you mention own their own ships? And move on their own, unbidden by other masters? Then they are pretty powerful already, and the Captain of such a ship could certainly curry favour with the Dark Gods. The heretics that stay in realspace and don't hide where the Astronomican don't shine (namely the Eye, Vortex, Maelstrom or some such) generally don't last long; conversely, going into a previously mentioned warpstorm with just a navigator is considered suicide (by the navigators themselves, see p. 327 of the Black Crusade Core Rulebook, in the first paragraphs).
So either the Heretics have another, reliable way of navigating the Vortex or... or nothing. They just die or get lost.
Most of the Lost and Damned that you describe are either the troops of those powerful Champions, and generally have little say in their fate, or live on chaotic planets and rarely take ships to go anywhere.
The only heretics that I would see (grudgingly) use the Astronomican are those that try to pass for Imperials.
Edited for clarity, grammar, spelling, and citations.
Edited by K0balt, 30 August 2013 - 01:38 PM.