In my current game, a Construction Ship from a new alien race popped out a dead end system that I had previously fully surveyed and started building a jump gate on the jump point to that dead end system in Sol. This tells me there is a hidden jump point in that system because there is no way for the ship to have gotten there otherwise.
Is there a way to find the jump point that the gate builder came through, and presumably the Jump Gate it built there? I have already sent my grav survey fleet back into the dead end system and manually resurveyed all 30 survey locations. This did not turn up a jump gate or anything else.
Am I effectively in a position where an alien race to Sol orbit and I can't find where they are coming from?