Tau Cygna V

Tau Cygna V is a Class H planet in the Tau Cygna system within the de Laure belt. It was annexed from the Federation by the Sheliak Corporate in the 2255 Treaty of Armens.

In 2274, the SS Artemis crash-landed on the planet's surface. One third of the crew died of the hyperonic radiation. The survivors established a new colony. In 2366, the population reached 15,253 people, which, however, had to be evacuated, due to the Sheliak claim on the planet. (TNG: "The Ensigns of Command")

(From Memory Alpha)