A sub-sector is an Imperial astrographical and political division of space that is one of the constituent territorial units of a sector of a segmentum of the Milky Way Galaxy. The size of a sub-sector varies according to local demands and stellar density.
A "typical" sector, if such a thing could be said to exist, might encompass 7 million cubic light years, equivalent to a cube with sides almost 200 light years long.
Sectors are divided into a variable number of sub-sectors, each usually comprising between 2 and 8 star systems within a 10 light year radius (some may encompass more systems -- others only 1).
This size is governed by the practical patrol ranges of Imperial starships. Because sub-sectors are divisions of worlds (rather than volumes of space) there are vast numbers of star systems within each sector which do not fall officially within a sub-sector. These are referred to as "inter-sectors" -- and are commonly better known as Wilderness Space, forbidden zones, empty space and frontier space.
Sources[]
- Battlefleet Gothic Rulebook, pp. 86, 117, (Inside Back Cover)
- Dark Heresy: Core Rulebook - Second Edition (RPG), pp. 322-323
- White Dwarf 139 (UK), "Interstellar Travel," pg. 18