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Aims. We conducted a systematic investigation of the microlensing data collected during the previous observation seasons for the purpose of re-analyzing anomalous lensing events with no suggested plausible models. Methods. We found that two anomalous lensing events, OGLE-2018-BLG-0584 and KMT-2018-BLG-2119, cannot be explained with the usual models based on either a binary-lens single-source (2L1S) or a single-lens binary-source (1L2S) interpretation. We tested the feasibility of explaining the light curves of the events with more sophisticated models by adding either an extra lens (3L1S model) or a source (2L2S model) component to the 2L1S lens system configuration. Results. We find that a 2L2S interpretation explains the light curves of both events well and that for each event there are a pair of solutions resulting from the close and wide degeneracy. For the event OGLE-2018-BLG-0584, the source is a binary composed of two K-type stars and the lens is a binary composed of two M dwarfs. For KMT-2018-BLG-2119, the source is a binary composed of two dwarfs of G and K spectral types and the lens is a binary composed of a low-mass M dwarf and a brown dwarf. 

Aims. We reexamine high-magnification microlensing events in the previous data collected by the KMTNet survey with the aim of finding planetary signals that were not noticed before. In this work, we report the planetary system KMT-2018-BLG-1988L, which was found from this investigation. Methods. The planetary signal appears as a deviation with ≲0.2 mag from a single-lens light curve and lasted for about 6 h. The deviation exhibits a pattern of a dip surrounded by weak bumps on both sides of the dip. The analysis of the lensing light curve indicates that the signal is produced by a low-mass-ratio ( q ~ 4 × 10 −5 ) planetary companion located near the Einstein ring of the host star. Results. The mass of the planet, M planet  = 6.8 −3.5 +4.7  M ⊕ and 5.6 −2.8 +3.8  M ⊕ for the two possible solutions, estimated from the Bayesian analysis indicates that the planet is in the regime of a super-Earth. The host of the planet is a disk star with a mass of M host  = 0.47 −0.25 +0.33  M ⊙ and a distance of D L  = 4.2 −.14 +1.8 kpc. KMT-2018-BLG-1988Lb is the 18th known microlensing planet with a mass below the upper limit of a super-Earth. The fact that 15 out of the 18 known microlensing planets with masses ≲10  M ⊕ were detected in the 5 yr following the full operation of the KMTNet survey indicates that the KMTNet database is an important reservoir of very low-mass planets. 

Aims. With the aim of interpreting anomalous lensing events with no suggested models, we conducted a project of reinvestigating microlensing data collected in and before the 2019 season. In this work, we report a multi-planet system, OGLE-2019-BLG-0468L, that was found as a result of this project. Methods. The light curve of the lensing event OGLE-2019-BLG-0468, which consists of three distinctive anomaly features, could not be explained by the usual binary-lens or binary-source interpretations. We find a solution that explains all anomaly features with a triple-lens interpretation, in which the lens is composed of two planets and their host, making the lens the fourth multi-planet system securely found by microlensing. Results. The two planets have masses of ~3.4  M J and ~10.2  M J , and they are orbiting around a G-type star with a mass of ~0.9  M ⊙ and a distance of ~4.4 kpc. The host of the planets is most likely responsible for the light of the baseline object, although the possibility of the host being a companion to the baseline object cannot be ruled out.