I would just like to add to this, that for the duration that SG-1 and Atlantis were running simultaneously, the new episodes themselves ran in parallel. SG-1 season 8 and Atlantis season 1 each released new episodes on the same night (two part season openers not withstanding), back-to-back. And while rare, they will later on make direct references to things happening episode-by-episode in the other.
Credit to /u/rinnieangel on Reddit, 12y ago.
01 - Stargate movie 02 - Stargate SG-1, episodes 1.1 to 8.2 03 - Stargate Atlantis, episodes 1.1 to 1.15 04 - Stargate SG-1, episodes 8.3 to 8.20 05 - Stargate Atlantis, episodes 1.16 to 2.1 06 - Stargate SG-1, episodes 9.1 to 10.2 07 - Stargate Atlantis, episodes 2.2 to 3.4 08 - Stargate SG-1, episodes 10.3 to 10.12 09 - Stargate Atlantis, episodes 3.5 to 3.19 10 - Stargate SG-1, episodes 10.13 to 10.20 11 - Stargate: The Ark of Truth 12 - Stargate Atlantis, episodes 3.20 to 5.1 13 - Stargate: Continuum 14 - Stargate Atlantis, episodes 5.2 onwards. 15 - Stargate Universe, AllThere is also this canon and chronological list. From /u/bill
I would just like to add to this, that for the duration that SG-1 and Atlantis were running simultaneously, the new episodes themselves ran in parallel. SG-1 season 8 and Atlantis season 1 each released new episodes on the same night (two part season openers not withstanding), back-to-back. And while rare, they will later on make direct references to things happening episode-by-episode in the other.