With the rules for travel through the warp established, one thing missing is rules for communicating across interstellar distances. These rules are as follows:
Astropaths gain one additional starting talent:
Astral Telepathy you were soul-bound to the Emperor, allowing your thoughts to be heard across the void – and you to hear the thoughts of others so cast into the warp. To send or receive an astropathic message, you need to successfully test Psyniscience.
To determine the time it takes for an astropathic message to reach its destination, use the Warp Time section of the Jump Table (see Warp Travel) but read it as the time passing in real space between sending and arrival.
Circumstances may modify both the time (e.g., a message sent along a main astropathic duct might need a one smaller unit of time to arrive – weeks becoming days, days becoming hours, and so on) or the difficulty of the Psyniscience test (e.g., severe warp storms might impose a -2 penalty to sending a message, whereas receiving a message at an astropathic relay station might benefit from a +1 bonus).