Board Thread:Warhammer 40k General Discussion/@comment-25618639-20150515003436/@comment-6078851-20150517152924

probably. it's been mentioned a few times that the novel 'unremembered empire' (which i havn't read, so maybe someone who has can give you the specifics) tell of the use of warp-beacons which simulate the astronomican in providing a navigation point within the warp. so it's safe to assume that if 40k's declining, and inferior, technology can create warp-beacons, then the previous empire almost assuredly would have had warp-beacons also.

such beacons only mimic the astronomican though - the power of the astronomican (emps basically) is so strong that it provides a beacon that stretches across most, if not all, of the galaxy. the strength of the astronomican is what allows ships to safely travel across massive portions of the galaxy in a single trip through warpspace, but when using warp-beacons ships can only travel safely through the warp using relatively short 'hops'. essentialy such beacons allow for (relatively) safe journeys through the 'shallows' of the warp, whereas the astronomican is bright enough to allow (relatively) safe journeys through the 'deeps': the deeper you travel in the warp the faster you travel across realspace distances, but the deeper you go increases the chances of becoming lost.

the previous empire did occasionally risk deep-warp travel to get somewhere quickly, but only in the direst of emergencies because the odds where exceptionally high that deep travelling ships would never re-emerge from the warp. i can't remember if i've read that the previous empire actually had warp-beacons, but given the size of their empire they must've had at least a safe and reliable system of traversing the shallows.