P7X-009 was the destination for Prometheus on its official maiden voyage (6.20 "Memento"). SG-1 was on board the vessel for its shakedown cruise. Though Prometheus had been in space before, this was its first mission with full crew complement. The entire mission was not scheduled to take more than a few hours. Unfortunately, en route, the X-303 developed problems with its hyperdrive and never reached P7X-009.
Daniel Jackson later mentioned P7X-009, but confused it with P3X-744, Tagrea, where Prometheus actually ended up on that failed shakedown cruise (7.13 "Grace"). Note that Dr. Jackson was not on SG-1 during the Prometheus early missions.
--Aurora 08:42, 28 June 2006 (PDT)