KMT-2025-BLG-1616Lb: First Microlensing Bound Planet From DREAMS

Abstract We present observations and analysis of the bound planetary microlensing event KMT-2025-BLG-1616. The planetary signal was captured by the Korea Microlensing Telescope Network and the Dark Energy Camera Rogue Earths and Mars Survey (DREAMS). DREAMS’s minute-cadence observations break the central/resonant degeneracy in the binary-lens models. The color of the faint source star ( I = 22) is measured from the DREAMS’s r − z color. The planetary system has a planet-host mass ratio of q ∼ 5 × 10 −4 . A Bayesian analysis yields a host-star mass of ∼0.3 M ⊙ , a planetary mass of ∼40 M ⊕ , a projected planet-host separation of ∼1.6 au, and a lens distance of ∼7.5 kpc. Based on the photometric precision achieved by DREAMS for this event, we simulate free-floating planet (FFP) detections and find that DREAMS is sensitive to Mars-mass FFPs in the Galactic bulge and Moon-mass FFPs in the Galactic disk.