The Epsilon IX sector, also known as the Epsilon Sector, was a region of space. The Epsilon Pulsar Cluster was located in this sector.

In 2365, the USS Enterprise-D was assigned to perform an astronomical survey of the Epsilon Pulsar Cluster. (TNG: "Samaritan Snare")

This sector was only mentioned in dialogue.
According to Star Trek Encyclopedia (4th ed., vol. 1, p. 249), this may have been the location of the Epsilon IX station from Star Trek: The Motion Picture.
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