Planet in close relative proximity to P3W-451, a planet on the edge of a newly formed black hole. After dialing 451 and being unable to shut down the wormhole Stargate Command detonated a focused explosive device directed at the wormhole, forcing the other end to "jump" from 451 to P2A-270.
This did the planet no harm, and allowed Earth to simply shut down its gate as normal. (There is no indication that a team from Earth ever visited the planet.)
HOME TO - Unknown
FIRST APPEARED - N/A
A Matter of Time - The S.G.C. forces the Stargate to jump to P2A-270 in order to escape the effects of a black hole on the other end.