The fact that editions previous to Mongoose Traveller have been focused on the Third Imperium has been cited by many as a turn off as the mass of canon grew due to official and fan activity.
But then you get this
Just use your mouse wheel to zoom and the left button to drag the map around. If you zoom in far enough you will see the Universal World Profile (UWP) for each world. Of course if you are an old traveller hand like me you have most of the codes already memorized.
Despite the mass of canon you should not feel intimidated by the mass of canon behind the Third Imperium. Because despite the quantity the developers of traveller did a smart thing. Nearly all of what considered canon is high level detail. So high that when you pick a subsector or sector to play you still get to create all the specific details. GURPS Traveller talks about Dark Imperiums, Grey Imperiums and White Imperiums styles of play and how they all work without contradicting the core material.
Only a handful of planets and subsector are detailed to any great extent. In the Spinward Marches this amounts to Aramis Subsector (the Traveller Adventures), Regina Subsector (various), Tarsus, Bowman Belt, Mithril, Vanejen, Fulacin, and a handful of other worlds.
However due to literally decades of work, you can find fan created material for just about any part of the Imperium and it's frontiers. This helps when you run short of prep time or ideas.
More critical hit goodness (courtesy of Peter Dell'Orto)
56 minutes ago