OGLE-2018-BLG-0799Lb: a Sub-Saturn-Mass Planet Orbiting a Very Low Mass
  Dwarf
  We report the discovery and analysis of a sub-Saturn-mass planet in the
microlensing event OGLE-2018-BLG-0799. The planetary signal was observed by
several ground-based telescopes, and the planet-host mass ratio is $q = (2.65
\pm 0.16) \times 10^{-3}$. The ground-based observations yield a constraint on
the angular Einstein radius $\theta_{\rm E}$, and the microlens parallax
$\pi_{\rm E}$ is measured from the joint analysis of the Spitzer and
ground-based observations, which suggests that the host star is most likely to
be a very low-mass dwarf. A full Bayesian analysis using a Galactic model
indicates that the planetary system is composed of an $M_{\rm planet} =
0.22_{-0.06}^{+0.19}~M_{J}$ planet orbiting an $M_{\rm host} =
0.080_{-0.020}^{+0.080}~M_\odot$, at a distance of $D_{\rm L} =
4.42_{-1.23}^{+1.73}$ kpc. The projected planet-host separation is $r_\perp =
1.27_{-0.29}^{+0.45}$ AU, implying that the planet is located beyond the
snowline of the host star. However, because of systematics in the Spitzer
photometry, there is ambiguity in the parallax measurement, so the system could
be more massive and farther away.
