The Calixis sector is located at the very edge of the main galactic disk, but seeing as it is adjacent to Scarus Sector is seems likely the main bulk of Calxis is at the rimward edge of the Perseus Arm. If so then stellar density is probably comparable to that found around Sol, maybe somewhat lower on average. Let us say 0,5 star per cubic parsec (half of Sol's stellar neighborhood). If we assume that Calixis sector is something like 1000x1000x1000 light-years in size (a wild but probably also very low guesstimate) that would give Calixis sector something like 13.5 million stellar objects. If we assume G-class stars to be the most conductive to the formation of life-sustaining worlds there will be around 1 million of those in Calixis. If we allow for some variation (its a strange galaxy after all) for other spectral types (K + F mostly) we get even more potentially world-bearing systems...2-3 million or so. Of course, not all will have naturally habitable systems, but that's not really a limit in the ultra-tech universe of 40k. So what I'm saying is this - the worlds on the map represent just a tiny fraction of the worlds out there; a very tiny fraction...and who knows what is hidden in the deep dark...