Just in case you're a bit confused by the jumping around, I'll provide a little insight into my galaxy.
I am trying to base it on the real Milky Way galaxy, given what we know or don't know. I found this site recently, http://galaxymap.org/, which is absolutely amazing! I will have to make sure I modify a few things in my own map, but for the most part it doesn't matter, as in 12,000+ years the map will be well documented and stars etc. will have real names instead of numbers and their properties well known. Our understanding of the universe will be beyond anything we can imagine now.
The Milky Way is a spiral galaxy consisting of billions of stars and a dense bar core (usually depicted as a very bright spot). Earth is located in the Orion spur. There are quite a few stars like our own sun within a few hundred light years, and when humankind is capable of that kind of travel, no doubt colonies will follow. If no planets orbit those stars at Earth-like readiness, man-made structures will no doubt be built where conditions are most ideal.
If, from Earth, you could look toward the core, there would be a large section of the galaxy behind it that you can not see. This is the umbra, or shadow, so to speak. I decided it is a good place for nefarious types to have space wars without Earthlings being able to see it. This area is my Penumbra.
All the colonies around Sol (Earth's sun) and the neighboring star systems joined together for commerce and what-not, calling their tenuous alliances the League. This being on the opposite side of the Penumbra, it makes a great place for the "good guys." Ha. League uses "antiquated" Sol-centered mapping of the galaxy.
Facing the Core from Sol, on the right hand side, beyond the last of the League-affiliated colonies, is the quadrant of the galaxy where the Coalition is. If the League is a confederacy, the Coalition is unified under a militarized central government. The border between the Penumbra and Coalition has some scientific anomalies (which I made up) that make it a challenge to dwell in. Coalition uses a Core-centered navigational system.
And last but not least, facing the Core on the left is a quadrant that has pretty much nothing to offer - a few resources for mining or other basic industries, but it's kind of like the back alley. This is the Fringe, and it has no central government and no strong affiliations - just whoever dared to go out there with a frontier attitude.
In the story I have a brief scene which refers to radians. I use the radians off the galactic core, not the Sun-Centric version shown here. However, they're both pretty close in that region, so it's still a good reference.
Please don't laugh too loudly at my crude artistic rendering of the spiral arms. Thanks.