Your group has pierced the veil of Dark Astoria and set a teleport beacon there.
How to Get
One obtains the Dark Astoria Beacon supergroup badge by visiting all the Dark Astoria exploration badge locations while in supergroup mode.
Note that visiting these locations while not in supergroup mode will not advance towards earning this beacon badge, even though it will earn the personal exploration badge for that marker.
The Dark Astoria Beacon Badge location is (3580, 0, 631.5), northeast of the Barca Plaza marker.