Astronomican: The Astronomican is the homing beacon maintained by the Adeptus Astronomica. Without it long distance travel would be almost impossible and ships would regularly be lost in the warp. The Astronomican can also be used as a signal from which to reset the clocks of a ship. Due to the instabilities and anomolies of the warp, time may not have passed in real space at the same rate as it did in warp space.
The Astronomican is powered by the draining of thousands of Chosen in the Chamber of the Astronomican. Each psyker my last only a few months, but the power drained from them and fed through the Emperor allows ships to travel without fear.
The Astronomican itself is located within the Adeptus Astronomica's stronghold in the Himalayas, and is transmitted from a dome carved in to the top of one of the mountains.
Source: Unknown by unknown, Draco by Ian Watson
Submitter: IBBoard
Hive World Terra