We report the discovery and analysis of the planetary microlensing event OGLE-2017-BLG-0406 , which was observed both from the ground and by the Spitzer satellite in a solar orbit .
At high magnification , the anomaly in the light curve was densely observed by ground-based-survey and follow-up groups , and it was found to be explained by a planetary lens with a planet/host mass ratio of q = 7.0 \times 10 ^ { -4 } from the light-curve modeling .
The ground-only and Spitzer - “ only ” data each provide very strong one-dimensional ( 1-D ) constraints on the 2-D microlens parallax vector { \mbox { \boldmath$ \pi$ } } _ { E } .
When combined , these yield a precise measurement of { \mbox { \boldmath$ \pi$ } } _ { E } , and so of the masses of the host M _ { host } = 0.56 \pm 0.07 M _ { \odot } and planet M _ { planet } = 0.41 \pm 0.05 M _ { Jup } .
The system lies at a distance D _ { L } = 5.2 \pm 0.5 { kpc } from the Sun toward the Galactic bulge , and the host is more likely to be a disk population star according to the kinematics of the lens .
The projected separation of the planet from the host is a _ { \perp } = 3.5 \pm 0.3 au , i.e. , just over twice the snow line .
The Galactic-disk kinematics are established in part from a precise measurement of the source proper motion based on OGLE-IV data .
By contrast , the Gaia proper-motion measurement of the source suffers from a catastrophic 10 \sigma error .