Archanis IV

Archanis IV is the sole Class M planet in the Archanis System and the only inhabited one as well. It is known for it's huge, relatively flat land masses. Prairies, savannahs, and grasslands are the norm, with only a single mountain range on the entire planet. It also has the distinction of enduring an eclipse every 2 months, 16 days, and 14 hours thanks to it's bigger brother Archanis II. The gas supergiant completely blocks out the planet's sun for a period of 28 hours and 25 minutes each eclipse.

The planet had been under the control of the Klingon Empire for at least a century when they were forced to hand it over to the Federation, per the stipulations of the Treaty of Organia. Once in the Federation's hands, outposts were immediately established given the strategic importance of the planet. These soon gave way to a complete Starfleet base called Reagan Station.

Chancellor Gowron specifically named Archanis IV as one of the locations that the Federation had to return in late 2373. The planet and the station were quickly taken at the start of the Second Federation-Klingon War. It was returned upon the restoration of the Khitomer Accords. (DS9: "Broken Link", "Apocalypse Rising")