My guess would be multicrew, but your first answer is just as plausible.Interesting - do you know if it was like that before (I don't remember it being mapped).
4A still shows as unmapped right now
Two ways I was thinking, but haven't tried:
1) Get the Gnosis to send you to prison, not sure if you keep your find if you don't actually die, but hand yourself in
2) Multicrew. Again, not sure if someone could multicrew in and claim the mapping
Edit: I have a pic showing the star was not discovered when we arrived, so I guess it is someone on the expedition