OGLE-2013-BLG-1125/MOA-2013-BLG-584: Discovery of a gas giant orbiting an M dwarf

During the summer season of 2013, survey and follow-up teams using conventional and robotic telescopes combined their efforts to identify and characterize planetary deviations in microlensing events towards the Galactic bulge. We report the discovery and characterization of a planetary system in the microlensing event OGLE-2013-BLG-1125/MOA-2013-BLG-584. We analyzed photometric data from OGLE and MOA surveys, as well as LCO, μFUN, and Mindstep follow-up telescopes to model the microlensing light curve. We also used data from the Keck II telescope collected in 2018 to obtain additional constraints on the lensing system. We found a Saturn-mass planet of mass M_ ̊m p =105 =0.139 M_⊕ orbiting a low-mass host star M_ ̊m L M_⊙ at 1.00 kpc from Earth. This discovery adds to the small sample of giant planets orbiting low-mass stars and provides constraints on planet formation theories.