From what I can glean from Blood Reaver, about the only source to provide an account of this, Warp Travel in such areas without the Astronomicon seems to be a matter of familiarity more than anything. Someone else may have a better answer than me because I've honestly never really looked into it. :dunno:

 

This does indeed seem to be the case. When Octavia is directed to take them to the Eye she was to do so by her sense alone.

 

So I guess what does that exactly mean? Having previous knowledge of the area, or basically being able to feel your way blind, feeling your way through the Warp?

 

Well, for my money, the Immaterium seems to be something of a living thing unto itself. It has currents and tides, and most likely a talented enough psyker could indeed feel these tides and get a sense of how they flowed and approximately where. In my varied research, it seems to be possible to navigate through the warp in those places if you have powerful enough navigators plotting your course. I believe the Grey Knights have some of the most gifted among these navigators and can make regular and safe journeys into places like the Eye of Terror without much in the way of hassle. Does make a strong case for it being entirely likely that a psyker's power can directly reflect his ability to navigate the warp without help.

 

Before the Astronomican, Navigators used to still make Warp jumps just of a much more limited scope. 'Now', a jump can take you tens of thousands of light years(?), 'then' the jump would only be a couple of light years, with the ship translating back to reality so the Navigators could get a fix on their position; then they did it all over again. Faster than other modes of travel, but not God-Emperor fast!
From this, I imagine jumps in the Eye would be mainly short, with Navigators maybe building experience of a set of Warp currents, giving those who don't rely on the Astronomican, maybe, a more instinctual way of reading the Warp. Possibly, those with Daemonic patrons/pacts may be given help so as to make longer jumps.

GFP

 

thanks for all the replies.

 

In the Grey Knights novel, Hammer of Daemons, there are a few attempts to describe the process of traveling through the Eye of Terror, but if memory serves it was more of a point-and-shoot process for navigation.

 

So I guess the point of the Cadian Gate, is that within the Eye, most of your jumps would be short so that you didn't get thrown off track too much, whereas a stable area like the Cadian Gate allows for longer range jumps.