Captain, there's something out there."
"I need a better description than that, Mr. Kim!"
"I… don't know. I'm reading – I'm not sure what I'm reading.Harry Kim and Kathryn Janeway
The Caretaker's array was a large space station in the Delta Quadrant not far from Ocampa. It was seventy-five thousand light years from the Badlands and fifty thousand from the galactic core. Built by the Nacene and powered by a tetryon reactor, the array served as a location from which the Caretaker could protect and serve the Ocampa. It acted as an energy source for the underground Ocampa settlements and continually pumped energy into the Ocampa city for nearly 1,500 years.
It contained medical and holographic facilities and was armed with energy weapons that were also capable of transmitting energy to Ocampa. In addition, it was capable of generating a displacement wave that could drag ships from other parts of the galaxy.
After the Caretaker died in early 2371, the array was ordered to be destroyed by Captain Kathryn Janeway of the USS Voyager, in order to prevent the Caretaker's advanced technology from falling into the hands of the Kazon. A pair of tri-cobalt devices was enough to trigger the station's destruction. (VOY: "Caretaker", "The Voyager Conspiracy")
In the first draft script for the episode "Caretaker", the Caretaker's array was initially described as "a huge, eerie alien space Array... an ominous piece of space hardware... sending out pulses of energy arcing into space for reasons we cannot immediately understand... our first impression of it might be as some strange kind of weird lighthouse in space."
After the events of "Cold Fire", the Nacene, also known as the Caretakers, were mentioned in the episode "The Voyager Conspiracy", where Seven of Nine is concerned that the power source for Tash's catapult is one of the generators from the Caretaker's array. The Caretaker and his array are mentioned in passing in the episodes "Projections", "Night", and "Endgame".