Flight of a Thousand Years
North and South do not work when referring to directions within the galaxy. Instead, interstellar navigators have established a set of conventions when referring to astrographic directions, which have achieved widespread acceptance.
Toward the galactic core is coreward; away from it, in the direction of the rim, is rimward. In the direction that the galaxy is rotating is spinward, while the opposite direction is trailing.
These directions are in widespread use in describing Imperial features and businesses. For example, the Spinward Marches is a sector at the extreme spinward fringe of the Imperium; Rimward Lines is an important interstellar transport company.
Finally, within the Imperium, the term coreward is also used to indicate the direction of Capital ( Core/Core 2118), the Imperial Core. There is some potential for confusion if the term is encountered out of context.