Regulus III

Regulus III was the inhabited third planet in the Alpha Leonis system. This planet was approximately 79.299 light years (24.3 parsecs) from Sol and 300 light years (91.9 parsecs) from the Bajoran system.

In 2371, Jake Sisko's girlfriend, Mardah, was accepted to the Science Academy on this world. Benjamin Sisko was proud of her, stating that it was a good school. (DS9: "Fascination")

This planet was only mentioned in dialogue.
This planet's quadrant of origin was` inferred based on the position of its star as seen in the star chart appearing in the Star Trek: Discovery episode "Magic to Make the Sanest Man Go Mad".
In the Star Trek: Star Charts ("United Federation of Planets I"), in 2378, Regulus III was listed as a Federation member.

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