Delphi Ardu IV

Delphi Ardu IV is the fourth planet of the Delphi Ardu system. The planet is classified as class M, and prior to 2364, had only been charted by the Federation via long-range scans, which indicated no lifeforms--sentient or otherwise.

Delphi Ardu IV was an outpost of the extinct Tkon Empire, known as Outpost 63, and was guarded by a Portal. Portal 63 was encountered by away teams from the USS Enterprise (NCC-1701-D) and a Ferengi Marauder in 2364. 

Timothy Sinclair visited Delphi Ardu several times in the late 24th century, as part of his quest for knowledge of the Preservers. (: "Missing Person", "Odyssey, Part I", "Starkindler")