OGLE-2018-BLG-1428Lb: a Jupiter-mass planet beyond the snow line of a dwarf star

We present the analysis of the microlensing event OGLE-2018-BLG-1428, which has a short-duration (∼1 d) caustic-crossing anomaly. The event was caused by a planetary lens system with planet/host mass ratio q = 1.7 × 10^-3. Because of the detection of the caustic-crossing anomaly, the finite source effect was well measured, but the microlens parallax was not constrained due to the relatively short time-scale (t_E = 24 d). From a Bayesian analysis, we find that the host star is a dwarf star $M_{\rm host}=0.43^{+0.33}{-0.22} \ \mathrm{M}{\odot }$ at a distance $D_{\rm L}=6.22^{+1.03}{-1.51}\ {\rm kpc}$ and the planet is a Jovian-mass planet $M{\rm p}=0.77^{+0.77}{-0.53} \ M{\rm J}$ with a projected separation $a_{\perp }=3.30^{+0.59}_{-0.83}\ {\rm au}$ . The planet orbits beyond the snow line of the host star. Considering the relative lens-source proper motion of $\mu _{\rm rel} = 5.58 \pm 0.38\ \rm mas\ yr^{-1}$ , the lens can be resolved by adaptive optics with a 30 m telescope in the future.