Anyone know where I can find info on the origin of the astronomicon? I've played the TT game since the Rogue Trader and I was always under the impression that the astronomicon was tied to the golden throne and that they Emperor powered it by devouring countless souls of psykers every day. It is also frequently pointed out that if the Emperor were to die (dead, dead, not just mostly dead) the astronomicon would cease making warp travel (for humans) impossible (or at least anything more than the short jumps that charter vessels make) However, I've been reading the horus heresy series of novels and it is quite apparent that since the great crusades and horus heresy all took place before the Emperor was placed in the golden throne this calls into question my previous assumptions. It also seems likely that prior to the dark age of technology there must have been some way of warp travel to get all those humans scattered across the galaxy that the Emperor sets out to reconnect with in the great crusade. I haven't gone back yet to look through all my books, but I'm pretty sure I'm missing something. I'm curious for my Dark Heresy game when and how the astronomicon came about (in the game I'm running they have discovered an artifact that dates to pre-heresy crusading astartes and some discussion of the "imperial truth"). Thoughts?

Am not certain but i think it was the birth of slaanesh the made warp travel much more dangerous

The Astronomicon started when the Emperor got inturned in the Golden Throne and the High Lords of Terra took over runing the Imperium, Before that it was a net work of Astropaths that served as markers for the Navagators (just like the Current Era out beound the astronomicon) also I recall that before the upswing in Chaos activity that happened during the Hours Hearsery the Astropaths could sence the "Shadow" of a large enough consntrasion of Minds on the Warp.

Warp travel w/o navigators is possible. It's just more dangerous/difficult. You can't go very far and it's much less predictable. But, that's that. There are some passages in the warp where there is a 'calm flume' for thousands of years...transports can 'go in' and, provided they don't try to do much other than exit at a set time later and ride out the buffeting, they can arrive nicely happy at their destination. This, on the upside, permits the establishment of 'regular trade routes' and so forth.

The Astronomicon

Well, it's the guiding beacon for the Navigators. Navigators can still do stuff without it, but they're can't judge things quite as well. They're not...as effective. IIRC the astronomicon itself is fuelled by soul bound psykers. Its relation to the Emperor and the Golden Throne is, seemingly, that the Emperor is on the Golden Throne.

What we don't know:
- How the psykers are actually soul bound?
- Is the Golden Throne necessary for this?
- Did the Emperor regularly have to soul bind a century (or other number) of psykers every morning (or other frequency) to be shipped back to Earth when he was out Crusading?

It is said the Emperor 'directs' the light of the astronomicon, but to be utterly honest: I amn't sure even where to begin in speculating what that actually means. Is it a permanent psychic power which he's had in play for the better part of ten thousand years? Would it be affected if he stood too close to a pariah?

The History of the Thrones

Some books detail bits of the Emperor's psychic magickery which, IMO, are related (but in terms of the books this isn't explicit). Principally the candidates where there is 'any' information involved are largely Collected Visions , Mechanicum and Faith and Fire . I'll try to restrict important information to being irrelevent to the plot of the novels or merely that which is mentioned in Collected Visions .

There are multiple throne-like devices which seem to act as psychic tools for the Emperor. The most well known of these is the eponymous Golden Throne of Terra which, amongst other things, the Emperor used to create the Imperial Webway and maintain it. We also know it acts as a bit of a life-support device insomuch as it apparently still has the Emperor's soul tethered to his body (which rests on the throne). We also know that only the strongest of psykers could sit on the throne (the idea being, apparently, that Magnus would be returned to Terra and put on the throne) without dying quickly. There are items in other books which suggest the thrones are psychic boosters/foci/conductors/amplifiers/whatever.

My personal speculation (augmented by details in the books) is that the Golden Throne is a highly potent 'superpsychic multitool' which permits the user to do oodles of things with it. On thinking about it with regard to the question asked by the OP (whom I can't see right now ) I'd suggest that the Golden Throne is a necessary component in the Soul Binding ritual, but that it might not strictly be connected to the Astronomicon itself.

It might be, though. Could the Golden Throne be necessarily connected to the Imperial Webway, the Soul Binding ritual, the Astronomicon and perhaps even the power of the Saints and the Sororitas? The Halo devices might not be the only 'supermad ancient' technology to be left lying around the galaxy. Hell, I think I found the plot for Call of C'tan : The Throne of Terra and the Galaxias Kyklos Halo .

(Which, if you'll permit me to go off the deepend, is basically suggesting that the Throne Tech is leftover Old One stuff [superpsychic!] and the Halo Tech is [obviously?] C'tan Tech for turning folks/things into Necrons[or other]...)

Anyway, the Astronomicon is known to function when the Emperor is not on Terra, but how we don't know.

A reading recommendation

It doesn't really delve into the Astronomicon much/at all, but I do strongly recommend picking up a copy of Mechanicum at some point. If for no other reasons than it'll give you a bucket-load of similar quandries to worry about!

The astronomican is not necessarily linked with the Golden Throne in any way. It is powered generated from, housed in and powered by a ginormous chamber inside Everest, filled with powerful psykers. The psychic beacon these guys project is apparently directed by the God-Emperor. Presumably, without his guidance, it wouldn't form the roughly coherent beam across the (very approximate) galactic equivalent of the Tropic of Capricorn towards the Eastern Fringe, but would either form a shorter ranged spherical shell of psychic energy/data, or a more erratic beam, which point of aim would vary massively depending upon the position and attitude of Holy Terra with regard to, say, Ophelia VII (essentially becoming a lighthouse, itself travelling a small elliptical path).

All data going back to RT days (up until the word 'presumably', after which is my own speculation), from numerous sources

Before the Emperor's battle with Horus, it has been stated that the Emperor himself directed the beacon where ever he happened to be, as it was his psychic aura shining in the Warp. The choir of psykers isn't mentioned, so it's reasonable to presume that the Emperor himself generating the Astronomicon is how it worked, providing a point of reference for Navigators in the Warp.

However! After the battle with Horus, the Emperor is badly wounded and here we find mention of the choir of 10,000 psykers powering the beacon. The psykers are kept under the Himalayas in the Hall of the Astronomicon, and although they power the beacon, the Emperor directs it. The final battle with his protege psychically damaged the Emperor in some way, making this necessary.

Hope this helps - this is my first post so be kind.

I agree with dazedandconfused about the emperor creating the beacon locally and with his psyker-breakfast only after him being thronebound.

Regarding the DAoT, I'd assume that either the navigator used thinking machines or other tech for enhancement or that the navigator gene was "purer", allowing a more precise view into the warp. An alternative solution has been posted on another site I don't recall at the moment: There was a second bloodline whose special skill was not seeing into the warp, but being seen over long distances. They were completely deadened to the effects of the warp (they'd have attracted daemons like moths to a flame), but unlike Nulls, they had a psychic presence allowing them to be used as reference points by the navigators.

Of course, it's entirely plausible that early Navigators would have aided in thier work by A.I. - they weren't initially illegal after all. True Artificial Intelligence was made illegal sometime around the start of the Great Crusade i believe (but i could be wrong).

From the Warhammer 40k (2nd ed) Codex Imperialis, page 6: The third factor which makes warp travel possible is the immeasureably powerful psychic beacon called the Astronomican. Broadcast by a choir of psykers from Earth, the Astronomicon reaches out through warp space, guiding spacecraft to their destination.

Page 12: Adeptus Astronomica: The Astronomicon is a psychic homing beacon which enables Navigators to steer their ships through the warp. It is essential for long distance space travel - without it the Imperium could not exist and mankind would quickly fall victim to the myriad perils that threaten its survival. The raw psychic power behind the Astronomicon is provided by a choir of ten thousand psykers.

Page 37: Some primary and secondary ranking psykers are reserved for the Adeptus Astronomica. They are handed over to complete their training under the auspices of that organization.

From Warhammer 40K 3rd ed core rulebook, page 100: For humans, warp travel is made possible by the presence of the Astronomicon. Projected from earth by a ten thousand strong choir of specially trained psychics, this beacon acts as a focus for ships in the warp. The prodigious amounts of mental energy needed to contribute to the Astronomicon drains a psyker of his life essence in a few short months and hundreds die every day, their shrivelled corpses replaced by legions of fresh recruits.

The psychic beam stretches across 70,000 light years of space, a focus for millions of commercial craft and warships to navigate through the tumultuous waves of the warp. The Navigators who guide human ships need the Astronomicon and without it the Imperial would fragment as warp travel become utterly hazardous and Imperial authority would be impossible to enforce. It is for these reasons that the beacon is often referred to as the Light of the Emperor...

From the Warhammer 40k 4th ed core rulebook, page 122: ... only the power of the psychic beacon known as the Astronomicon is bright enough to cross the vastness of the galaxy. Originating from Terra, the Astronomicon is projected through space from a vast, tiered chamber carved from a single moutain peek, where a ten thousand strong choir of trained psykers is agonisingly leeched of their life energies to empower its divine light. The sheer quantity of psychic energy generated is vast and only the mind of Emperor is might enough to direct such raw power.

From the Warhammer 40K 5th ed core rulebook, page 102: The third factor that makes Warp travel possible is the immeasurably powerful beacon of the Astronomicon, Broadcast from holy Terra by a choir of psykers and guided by the Emperors Will, this beacon reaches out through Warp space, where Navigators follow its guiding light.

... so, there you have it...

Gotta disagree with Dazedandconfused and Cifer: even prior to the Seige of Terra Malcador and Dorn discuss the great hall of the Astronomicon (in the Himalayasia region), carved into the peak of Everest. Events on Mars certainly reference the light of the astronomicon.

That said, that may be indicative of the Emperor setting up the psyker-choir powered Astronomicon as he retreated into his labs to mess about with the Golden Throne. Before this event I could believe he was powering it directly himself from wherever he was at the time.

Course, the fun thing about it all is that the Astronomicon isn't exactly static...

It would be kind of akin to having an artillery spotter on a very large, 5 acre roundabout doing 200km/h in the back of a truck yelling out directions of where he is and you're firing the shell from halfway across town somewhere across a tangent to him to roughly where you want it to land. In other words, something orbiting a sun doing 29.7km/second isn't exactly a really great point of reference when you're factoring in differences of 10's of 1000's of light years and narrowing things down to millionths of a degree of accuracy trying to hit something roughly the size of a solar system.

I guess it goes to explain why space travel with Cletus the inbred yokel pilot is sometimes full of fail in 40k... or why writers dont think things through very hard sometimes