KMT-2019-BLG-2073: Fourth Free-floating Planet Candidate with ? _E < 10 ?as

We analyze the very short Einstein timescale ($t_\rm E \simeq 7\,{\rm hr}$) event KMT-2019-BLG-2073. Making use of pronounced finite-source effects generated by clump-giant source, we measure radius $\theta_\rm 4.8\,\rm \mu as$, and so infer a mass $M = 59\,M_\oplus (\pi_\rm{rel}/16 \,\rm as)^{-1}$, where $\pi_\rm{rel}$ is lens-source relative parallax. find no significant evidence for host this planetary object, though one could be present at sufficiently wide separation. If so, it would detectable after about 10 years. This fourth isolated microlens with measured $\theta_\rm{E}<10\,\rm which argue useful threshold "likely free-floating planet (FFP)" candidate. outline new approach to constructing homogeneous sample giant-star finite-source/point-lens (FSPL) events, within subsample FFP candidates can statistically analyzed. illustrate using 2019 KMTNet data show that there large $\theta_\rm{E}$ gap between two 11 other FSPL events. such sharp features are more identifiable in selected on compared traditional identifying based $t_\rm{E}$.