M3A-716
From The Stargate Omnipedia
Planet located on the outer edge of the Pegasus Galaxy. M3A-716 is in relative proximity to M4F-788, the first link in the chain of the McKay-Carter intergalactic gate bridge linking Atlantis with the Midway Space Station (and from there Earth).
The planet is in the Ancient database in Atlantis.
DETAILS
HOME TO - Unknown
FIRST APPEARED - Midway
KEY EPISODE
Midway - M3A-716 appears in the Atlantis computer as a candidate for rerouting the gate bridge macro after M4F-788 becomes inaccessible.