No name. No visible membership. A series of dead drops, anonymous payments, and very specific knowledge that shouldn't exist.
Whoever they are, they've seen something — or they know something about the last time someone tried to wake the signal. They believe awakening it would be catastrophic. Not weapons-of-war catastrophic. Sector-extinction catastrophic.
The Hidden Faction are descendants of the original Ur survey team from two centuries ago. The survey found an Ur entity in deep stasis. They deliberately buried it and encoded a warning in a signal that only another Ur-capable intelligence could decode. They've been watching ever since.
6 segments. Fills when the Faction successfully contacts the crew, recovers artifacts, or delays other factions. When full: The crew finally understands what the signal actually is. The clock resets as "Point of No Return."