It was Diana's actions in DM number 6. And yes, there is still an Orrery of Worlds; but it has been restructured: first, the other world no longer hang off of Earth zero; second, the Orrery now has two poles: the Elseworld and Earth Omega. And unlike the original structure, this new structure isn't limited to 52 worlds; there is likely no upper limit to the number of worlds that it can support. Whether it's at the center of the Omniverse depends on whether or not the Omniverse has a center.