Calder II

Calder II is a Class M planet located in the Calder system, near the Romulan Neutral Zone in the Beta Quadrant. Hundreds of centuries ago, a group of Vulcan dissidents known as the Sakethans, build several burial mounds on the planet. The planet was also known for containing many Debrune artifacts. (Reference book: Star Trek: Star Charts).

By the early 2370s, Calder II was the location of a Federation science station and outpost. The outpost was protected by a type-4 deflector shield, and was armed with only two phaser banks for defensive purposes. (TNG episode: "Gambit, Part I").

Mirror Universe
In the mirror universe, the Sakethans hid a segment of the Stone of Gol inside the burial mounds on the planet. This segment of the stone was later recovered by treasure hunter, Jean-Luc Picard, in the early 2370s. (TNG novel: Glass Empires: "The Worst of Both Worlds").