Memory Gamma

Multiple realities
(covers information from several alternate timelines)

Memory Gamma was a planetoid in the Alpha or Beta Quadrant.

In 2367, the location of Memory Gamma was labeled on a tactical situation monitor in Captain Benjamin Maxwell's ready room on the USS Phoenix. (TNG: "The Wounded", okudagram)

In 2366, in an alternate timeline, during the Federation-Klingon War, Memory Gamma's position was labeled on a tactical situation monitor on the bridge and in the ready room of the USS Enterprise-D. (TNG: "Yesterday's Enterprise", okudagram)

This planetoid was only mentioned in writing.
It can't be deduced from the star chart in which quadrant Memory Gamma was located as there were planets and star systems from both quadrants spread throughout the chart.

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