Planet never visited by SG-1 in its first eight and a half years of operation. An SG-1 in another quantum reality visited 455, using the planet as their starting point to pass through Kallana's black hole an enter into a reality where Earth's Zero Point Module was still charged.
HOME TO -
people of PX7-455
FIRST APPEARED -
KEY EPISODE(S) -
Ripple Effect - Stargate Command makes contact with PX7-455, where the people assure them they have never laid eyes on SG-1.