I play a psyker in Dark Heresy 2nd Edition and using mainly the Divination tree. What I want to know is if other characters or NPCs in visual or auditory range can notice that I am using a power, since this does not appear to be specified in the book.
I am aware that there are many powers that are VERY obvious when you use them, but I am more interested in the ones that are potentially discreet (like Divination or Telepathy for example), and I am also aware that another psyker could detect me with Psyniscience. I am mainly after how it works in Dark Heresy but I can accept answers from other W40k RPGs (Black Crusade, Only War etc.) or simply W40k lore.