I don't know if anyone else has seen/pointed this out, but there is a way to find where the artifacts are on a map without researching and without letting someone else research. First, start the game, then, immediatley save and quit. Don't go to the main menu, but stay where you can look at credit and resource and fleet graphs. Through the bottom half of the screen, you will still be able to see planets at a galaxy view. Some of those planets will have the artifact symbol under them, without anyone having found an artifact there. You can then capture the planet, research for artifact, and every time there will be one of the powerful ones there, not the planetary ones. You might have to research twice.

Before anyone points it out, I know this doesn't belong under strategy, but I don't know where else to put it.