MOA-2013-BLG-220Lb: Massive Planetary Companion to Galactic-disk Host

We report the discovery of MOA-2013-BLG-220Lb, which has a super-Jupiter mass ratio q = 3.01 ± 0.02 × 10^-3 relative to its host. The proper motion, μ = 12.5 ± 1 mas yr^-1, is one of the highest for microlensing planets yet discovered, implying that it will be possible to separately resolve the host within ~7 yr. Two separate lines of evidence imply that the planet and host are in the Galactic disk. The planet could have been detected and characterized purely with follow-up data, which has important implications for microlensing surveys, both current and into the Large Synoptic Survey Telescope (LSST) era.