Intrasystem jump drive
From FreeSpace Wiki
The first intrasystem jump drive is the baseline subspace drive, developed before intersystem drives; it was present during the post-age of space exploration and colonization.
Intrasystem jump drives enable a ship to jump from one location in the system to another, quickly and (relatively) precisely. A jump drive of this kind does not need an intersystem subspace node, only the presence of a significant gravity well.
While subspace travel from one system to another in an intersystem jump takes a variable but relatively brief amount of time (the Lucifer's transit took fifteen minutes), an intrasystem jump is described as "nearly instantaneous."