[quote=@Necroes]
The ship is in combat, against eldar. The astropaths aren't going to be scanning the ship for psykers.
[/quote]

Uhhhh.. really? im pretty sure they would be doing that often, or at least periodically, since eldar are psyker af. it would be a bloody good boarding detection system for Eldar. If we assume the captain is half competent He would probably have one of them scanning the ship in search for Eldar Boarding actions. Which would have blown our cover, and i didnt think of it before. but not that you mentioned it, duh, of course they will.