Rabolum is a planet, the fourth in its star system. It is a "frontier world" that sat beyond the edge of Federation space until the 24th century. Rabolum is also located four light-years from a temporal vortex visited by the USS Equulus circa 2301.
In 2371, the government of Rabolum sent a number of technicians to study on Argelius II in order to improve the planet's industrial base. Among those students was a woman named Sharanna. (NF short story: "Through the Looking Glass")