OGLE-2018-BLG-1185b: A Low-mass Microlensing Planet Orbiting a Low-mass Dwarf

We report the analysis of planetary microlensing event OGLE-2018-BLG-1185, which was observed by a large number ground-based telescopes and $Spitzer$ Space Telescope. The light curve indicates low planet-host star mass ratio $q = (6.9 \pm 0.2) \times 10^{-5}$, is near peak wide-orbit exoplanet mass-ratio distribution. estimate host planet masses with Bayesian using measured angular Einstein radius under assumption that stars all have an equal probability to this planet. flux variation marginal, but still places constraint on microlens parallax. Imposing conservative should be $\Delta f_{\rm Spz} < 4$ instrumental units $M_{\rm host} 0.37^{+0.35}_{-0.21}\ M_\odot$ $m_{\rm p} 8.4^{+7.9}_{-4.7}\ M_\oplus$. A including full parallax from suggests smaller 0.091^{+0.064}_{-0.018}\ 2.1^{+1.5}_{-0.4}\ M_\oplus$, respectively. Future high-resolution imaging observations $HST$ or ELTs could distinguish between these two scenarios help reveal system properties in more detail.