Tethys III

Tethys III was the third planet in its star system. The planet was a hydrogen-helium gas giant with a frozen helium core orbiting a star. Located somewhere in the Alpha or Beta Quadrant, the planet was located several hundred light years away from the Ngame Nebula

In 2367, the crew of the USS Enterprise-D used the planet as a basis for concealing the Paxan homeworld in a T-Tauri type star system located within the nebula. (TNG: "Clues")

In the script, Tethys III was a Neptune-like planet.
"Tethys" was the daughter of the Greek gods Uranus and Gaia and was the eponym of one of Saturn's moons.