Spaceport Jonathan (W) was a spaceport in the Alpha or Beta Quadrant.
In 2328, the commercial transport SS Manoa arrived at this spaceport, and collected the passenger Kris Krosskove, then departed for Alpha Balder IV.
Records of this were accessed by Lieutenant Commander Data aboard the USS Enterprise-D in 2370, via the commercial transport database. (TNG-R: "Inheritance")
This spaceport was only mentioned in writing.