Publications (249)
Mass Production of 2023 KMTNet Microlensing Planets. II: Two Planets and A Brown Dwarf
Zhixing Li, Hongyu Li, Weicheng Zang +63
To expand the homogeneous microlensing planetary sample of the Korea Microlensing Telescope Network (KMTNet), we investigate six planetary candidates identified by the AnomalyFinde…
OGLE-2018-BLG-0532Lb: Cold Neptune With Possible Jovian Sibling
Yoon-Hyun Ryu, Andrzej Udalski, Jennifer C. Yee +34
We report the discovery of the planet OGLE-2018-BLG-0532Lb, with very obvious signatures in the light curve that lead to an estimate of the planet-host mass ratio $q=M_{\rm planet}…
Four Cold Giant Planets Discovered by High-Cadence Microlensing Surveys
Cheongho Han, Chung-Uk Lee, Andrzej Udalski +52
We report the discovery of four cold giant planets identified through the analysis of microlensing events detected by high-cadence surveys: OGLE-2016-BLG-0261, KMT-2025-BLG-0026, K…
OGLE-2018-BLG-1269Lb: A Jovian Planet With A Bright, Host
Youn Kil Jung, Andrew Gould, Andrzej Udalski +54
We report the discovery of a planet in the microlensing event OGLE-2018-BLG-1269, with planet-host mass ratio , i.e., times smaller than the Jupiter/Su…
KMT-2021-BLG-0240: Microlensing event with a deformed planetary signal
Cheongho Han, Doeon Kim, Hongjing Yang +18
The light curve of the microlensing event KMT-2021-BLG-0240 exhibits a short-lasting anomaly with complex features near the peak at the 0.1~mag level from a single-lens single-sour…
A free-floating-planet microlensing event caused by a Saturn-mass object
Subo Dong, Zexuan Wu, Yoon-Hyun Ryu +39
A population of free-floating planets is known from gravitational microlensing surveys. None have a directly measured mass, owing to a degeneracy with the distance, but the populat…
KMT-2021-BLG-1150Lb: Microlensing planet detected through a densely covered planetary-caustic signal
Cheongho Han, Youn Kil Jung, Ian A. Bond +49
Recently, there have been reports of various types of degeneracies in the interpretation of planetary signals induced by planetary caustics. In this work, we check whether such deg…
Analyses of anomalous lensing events detected from the UKIRT microlensing survey
Cheongho Han, Weicheng Zang, Andrzej Udalski +61
The United Kingdom Infrared Telescope (UKIRT) microlensing survey was conducted over four years, from 2016 to 2019, with the goal of serving as a precursor to future near-infrared…
KMT-2018-BLG-1292: A Super-Jovian Microlens Planet in the Galactic Plane
Yoon-Hyun Ryu, Maria Gabriela Navarro, Andrew Gould +22
We report the discovery of KMT-2018-BLG-1292Lb, a super-Jovian planet orbiting an F or G dwarf , which lies p…
Astrometric Detection of Double Gravitational Microlensing Events
Cheongho Han, Byeong-Gon Park, Wonyong Han +1
If a gravitational microlensing event is caused by a widely separated binary lens and the source approaches both lens components, the source flux is successively magnified by the i…
KMT-2019-BLG-2073: Fourth Free-Floating-Planet Candidate with $θ_\rm E < 10 \rmμas$
Hyoun-Woo Kim, Kyu-Ha Hwang, Andrew Gould +17
We analyze the very short Einstein timescale ($t_\rm E \simeq 7\,{\rm hr}$) event KMT-2019-BLG-2073. Making use of the pronounced finite-source effects generated by the clump-giant…
Four-Body Gravitational Microlensing Events Involving Both a Binary Lens and a Binary Source
Cheongho Han, Chung-Uk Lee, Andrzej Udalski +31
We present detailed analyses of three anomalous microlensing events--KMT-2021-BLG-0209, KMT-2021-BLG-0901, and OGLE-2025-BLG-0356--identified from a systematic re-examination of KM…
Reanalysis of the Gravitational Microlensing Event MACHO-97-BLG-41 based on Combined Data
Youn Kil Jung, Cheongho Han, Andrew Gould +1
MACHO-97-BLG-41 is a gravitational microlensing event produced by a lens composed of multiple masses detected by the first-generation lensing experiment. For the event, there exist…
MOA-2022-BLG-091Lb and KMT-2024-BLG-1209Lb: Microlensing planets detected through weak caustic-crossing signals
Cheongho Han, Chung-Uk Lee, Andrzej Udalski +66
The light curves of the microlensing events MOA-2022-BLG-091 and KMT-2024-BLG-1209 exhibit anomalies with very similar features. These anomalies appear near the peaks of the light…
OGLE-2019-BLG-0825: Constraints on the Source System and Effect on Binary-lens Parameters arising from a Five Day Xallarap Effect in a Candidate Planetary Microlensing Event
Yuki K. Satoh, Naoki Koshimoto, David P. Bennett +86
We present an analysis of microlensing event OGLE-2019-BLG-0825. This event was identified as a planetary candidate by preliminary modeling. We find that significant residuals from…
Variation of Spot-induced Anomalies in Caustic-crossing Binary Microlensing Event Light Curves
Heon-Young Chang, Cheongho Han
We investigate the pattern of anomalies in the light curves of caustic-crossing binary microlensing events induced by spot(s) on the lensed source star. For this purpose, we perfor…
KMT-2021-BLG-1547Lb: Giant microlensing planet detected through a signal deformed by source binarity
Cheongho Han, Weicheng Zang, Youn Kil Jung +52
We investigate the previous microlensing data collected by the KMTNet survey in search of anomalous events for which no precise interpretations of the anomalies have been suggested…
Degeneracy between Lensing and Occultation in the Analysis of Self-lensing Phenomena
Cheongho Han
More than 40 years after the first discussion, it was recently reported the detection of a self-lensing phenomenon within a binary system where the brightness of a background star…
KMT-2021-BLG-0912Lb: A microlensing super Earth around a K-type star
Cheongho Han, Ian A. Bond, Jennifer C. Yee +55
The light curve of the microlensing event KMT-2021-BLG-0912 exhibits a very short anomaly relative to a single-lens single-source form. We investigate the light curve for the purpo…
Stellar Contribution to the Galactic Bulge Microlensing Optical Depth
Cheongho Han, Andrew Gould
We estimate the optical depth to self-lensing by stars in the Galactic bulge using the HST star counts of Holtzman et al and Zoccali et al as extrapolated by Gould into the brown-d…
Systematic KMTNet Planetary Anomaly Search. XI. Complete Sample of 2016 Sub-Prime Field Planets
In-Gu Shin, Jennifer C. Yee, Weicheng Zang +63
Following Shin et al. (2023b), which is a part of the Systematic KMTNet Planetary Anomaly Search series (i.e., a search for planets in the 2016 KMTNet prime fields), we conduct a s…
Chromaticity of Gravitational Microlensing Events
Cheongho Han, Seong-Hong Park, Jang-Hae Jeong
In this paper, we investigate the color changes of gravitational microlensing events caused by the two different mechanisms of differential amplification for a limb-darkened extend…
OGLE-2023-BLG-0836L: The sixth microlensing planet in a binary stellar system
Cheongho Han, Andrzej Udalski, Youn Kil Jung +32
Light curves of microlensing events occasionally deviate from the smooth and symmetric form of a single-lens single-source event. While most of these anomalous events can be accoun…
MOA-2019-BLG-008Lb: a new microlensing detection of an object at the planet/brown dwarf boundary
E. Bachelet, Y. Tsapras, Andrew Gould +68
We report on the observations, analysis and interpretation of the microlensing event MOA-2019- BLG-008. The observed anomaly in the photometric light curve is best described throug…
Systematic KMTNet Planetary Anomaly Search. XIII. Complete Sample of 2021 Prime Field Planets
In-Gu Shin, Jennifer C. Yee, Weicheng Zang +40
The Systematic KMTNet Planetary Anomaly Search series was conducted using the KMTNet data archived from to . From this first phase of the series, we reported a total o…
OGLE-2015-BLG-1771Lb: A Microlens Planet Orbiting an Ultracool Dwarf?
Xiangyu Zhang, Weicheng Zang, Andrzej Udalski +31
We report the discovery and the analysis of the short (tE < 5 days) planetary microlensing event, OGLE-2015-BLG-1771. The event was discovered by the Optical Gravitational Lensing…
Limits of Binaries That Can Be Characterized by Gravitational Microlensing
Doeon Kim, Yoon-Hyun Ryu, Byeong-Gon Park +5
Due to the high efficiency of planet detections, current microlensing planet searches focus on high-magnification events. High-magnification events are sensitive to remote binary c…
Four microlensing giant planets detected through signals produced by minor-image perturbations
Cheongho Han, Ian A. Bond, Chung-Uk Lee +63
We investigated the nature of the anomalies appearing in four microlensing events KMT-2020-BLG-0757, KMT-2022-BLG-0732, KMT-2022-BLG-1787, and KMT-2022-BLG-1852. The light curves o…
OGLE-2019-BLG-0468Lb,c: two microlensing giant planets around a G-type star
Cheongho Han, Andrzej Udalski, Chung-Uk Lee +37
With the aim of interpreting anomalous lensing events with no suggested models, we conducted a project of reinvestigating microlensing data in and before the 2019 season. In this w…
MOA-2020-BLG-208Lb: Cool Sub-Saturn Planet Within Predicted Desert
Greg Olmschenk, David P. Bennett, Ian A. Bond +74
We analyze the MOA-2020-BLG-208 gravitational microlensing event and present the discovery and characterization of a new planet, MOA-2020-BLG-208Lb, with an estimated sub-Saturn ma…
KMT-2016-BLG-1107: A New Hollywood-Planet Close/Wide Degeneracy
Kyu-Ha Hwang, Yoon-Hyun Ryu, Hyoun-Woo Kim +17
We show that microlensing event KMT-2016-BLG-1107 displays a new type of degeneracy between wide-binary and close-binary Hollywood events in which a giant-star source envelops the…
Systematic KMTNet Planetary Anomaly Search, Paper I: OGLE-2019-BLG-1053Lb, A Buried Terrestrial Planet
Weicheng Zang, Kyu-Ha Hwang, Andrzej Udalski +69
In order to exhume the buried signatures of "missing planetary caustics" in the KMTNet data, we conducted a systematic anomaly search to the residuals from point-source point-lens…
KMT-2021-BLG-1077L: The fifth confirmed multiplanetary system detected by microlensing
Cheongho Han, Andrew Gould, Ian A. Bond +45
The high-magnification microlensing event KMT-2021-BLG-1077 exhibits a subtle and complex anomaly pattern in the region around the peak. We analyze the lensing light curve of the e…
KMT-2024-BLG-0404L: A triple microlensing system consisting of a star, a brown dwarf, and a planet
Cheongho Han, Andrzej Udalski, Chung-Uk Lee +29
We have investigated the lensing event KMT-2024-BLG-0404. The light curve of the event exhibited a complex structure with multiple distinct features, including two prominent causti…
Systematic Reanalysis of KMTNet microlensing events, Paper I: Updates of the Photometry Pipeline and a New Planet Candidate
Hongjing Yang, Jennifer C. Yee, Kyu-Ha Hwang +52
In this work, we update and develop algorithms for KMTNet tender-love care (TLC) photometry in order to create an new, mostly automated, TLC pipeline. We then start a project to sy…
A Comparison of the Intrinsic Shapes of Two Different Types of Dwarf Galaxies: Blues Compact Dwarfs and Dwarf Ellipticals
Eon-Chang Sung, Cheongho Han, Barbara +3
We measure the apparent shapes for a sample of 62 blue compact dwarf galaxies (BCDs), and compare them with the apparent shapes for a sample of 80 dwarf elliptical galaxies (dEs).…
An Additional Application of the Space Interferometry Mission to Gravitational Microlensing Experiments
Cheongho Han, Tu-Whan Kim
Despite the detection of a large number of gravitational microlensing events, the nature of Galactic dark matter remains very uncertain. This uncertainty is due to two major reason…
OGLE-2018-BLG-0971, MOA-2023-BLG-065, and OGLE-2023-BLG-0136: Microlensing events with prominent orbital effects
Cheongho Han, Andrzej Udalski, Ian A. Bond +60
We undertake a project to reexamine microlensing data gathered from high-cadence surveys. The aim of the project is to reinvestigate lensing events with light curves exhibiting int…
Determination of Stellar Ellipticities in Future Microlensing Surveys
Cheongho Han, Heon-Young Chang
We propose a method that can determine the ellipticities of source stars of microlensing events produced by binary lenses. The method is based on the fact that the products of the…
KMT-2019-BLG-1715: planetary microlensing event with three lens masses and two source stars
Cheongho Han, Andrzej Udalski, Doeone Kim +61
We investigate the gravitational microlensing event KMT-2019-BLG-1715, of which light curve shows two short-term anomalies from a caustic-crossing binary-lensing light curve: one w…
KMT-2021-BLG-0284, KMT-2022-BLG-2480, and KMT-2024-BLG-0412: Three microlensing events involving two lens masses and two source stars
Cheongho Han, Andrzej Udalski, Ian A. Bond +59
We carried out a project involving the systematic analysis of microlensing data from the Korea Microlensing Telescope Network survey. The aim of this project is to identify lensing…
MOA-2016-BLG-319Lb: Microlensing Planet Subject to Rare Minor-Image Perturbation Degeneracy in Determining Planet Parameter
Cheongho Han, Ian A. Bond, Andrew Gould +42
We present the analysis of the planetary microlensing event MOA-2016-BLG-319. The event light curve is characterized by a brief ( days) anomaly near the peak produced by mi…
Vertical Shear Instability in Thermally-Stratified Protoplanetary Disks: II. Hydrodynamic Simulations and Observability
Han-Gyeol Yun, Woong-Tae Kim, Jaehan Bae +1
We conduct three-dimensional hydrodynamic simulations to investigate the nonlinear outcomes and observability of vertical shear instability (VSI) in protoplanetary disks. Our model…
Correlations Between Planetary Microlensing Parameters
Cheongho Han, Kyu-Ha Hwang, Yoon-Hyun Ryu
Characterization of microlensing planets requires modeling of observed light curves including many parameters. Studying the dependency of the pattern of light curves on the lensing…
Additional Information from Astrometric Gravitational Microlensing Observations
Cheongho Han
Astrometric observations of microlensing events were originally proposed to determine the lens proper motion with which the physical parameters of lenses can be better constrained.…
Systematic KMTNet Planetary Anomaly Search, Paper VII: Complete Sample of Planets from the First Four-Year Survey
Weicheng Zang, Youn Kil Jung, Hongjing Yang +36
We present the analysis of seven microlensing planetary events with planet/host mass ratios : KMT-2017-BLG-1194, KMT-2017-BLG-0428, KMT-2019-BLG-1806, KMT-2017-BLG-100…
Microlensing brown-dwarf companions in binaries detected during the 2022 and 2023 seasons
Cheongho Han, Ian A. Bond, Andrzej Udalski +63
Building on previous works to construct a homogeneous sample of brown dwarfs in binary systems, we investigate microlensing events detected by the Korea Microlensing Telescope Netw…
Four sub-Jovian-mass planets detected by high-cadence microlensing surveys
Cheongho Han, Doeon Kim, Andrew Gould +57
With the aim of finding short-term planetary signals, we investigated the data collected from the high-cadence microlensing surveys. From this investigation, we found four planetar…
OGLE-2019-BLG-0304: Competing Interpretations between a Planet-binary Model and a Binary-source + Binary-lens model
Cheongho Han, Andrzej Udalski, Chung-Uk Lee +31
We analyze the microlensing event OGLE-2019-BLG-0304, whose light curve exhibits two distinctive features: a deviation in the peak region and a second bump appearing ~days…
Effect of Binary Source Companions on the Microlensing Optical Depth Determination toward the Galactic Bulge Field
Cheongho Han
Currently, gravitational microlensing survey experiments toward the Galactic bulge field utilize two different methods of minimizing blending effect for the accurate determination…
Gravitational Microlensing: A Tool for Detecting and Characterizing Free-Floating Planets
Cheongho Han, Sun-Ju Chung, Doeon Kim +4
Various methods have been proposed to search for extrasolar planets. Compared to the other methods, microlensing has unique applicabilities to the detections of Earth-mass and free…
Astrometric Microlensing: A Channel to Detect Multiple Lens Systems
Cheongho Han
If a source star is gravitationally microlensed by a multiple lens system, the resulting light curve can have significant deviations from the standard form of a single lens event.…
Planetary Lensing Signals of High-Magnification Events under Severe Finite-Source Effect
Cheongho Han, Doeon Kim
We investigate the effect of a finite source on the planetary-lensing signals of high-magnification events. From this, we find that the dependency of the finite-source effect on th…
Characterization of Stellar Spots in Next-Generation Microlensing Surveys
Kyu-Ha Hwang, Cheongho Han
One of the important microlensing applications to stellar atmospheres is the study of spots on stellar surface provided by the high resolution of caustic-crossing binary-lens event…
Galactic Bulge Pixel Lensing Events
Cheongho Han
Gould & DePoy proposed a pixel lensing survey towards the Galactic bulge using a small aperture (~65 mm) camera with a large pixel size (10") detector and deliberately degraded opt…
Distribution of Caustic-Crossing Intervals for Galactic Binary-Lens Microlensing Events
Cheongho Han, Seong-Hong Park, Yong-Sam Lee
Detection of caustic crossings of binary-lens gravitational microlensing events is important because by detecting them one can obtain useful information both about the lens and sou…
Analysis of the full Spitzer microlensing sample I: Dark remnant candidates and Gaia predictions
Krzysztof A. Rybicki, Yossi Shvartzvald, Jennifer C. Yee +70
In the pursuit of understanding the population of stellar remnants within the Milky Way, we analyze the sample of microlensing events observed by the Spitzer Space Teles…
Signs of Planetary Microlensing Signals
Cheongho Han, Kyongae Chang
An extrasolar planet can be detected via microlensing from the perturbation it makes in the smooth lensing light curve of the primary. In addition to the conventional photometric m…
Mass Production of 2021 KMTNet Microlensing Planets II
Yoon-Hyun Ryu, In-Gu Shin, Hongjing Yang +18
We continue our program of publishing all planets (and possible planets) found by eye in 2021 Korea Microlensing Telescope Network (KMTNet) online data. We present 4 planets, (KMT-…
Microlensing Zone of Planets Detectable through the Channel of High-Magnification Events
Cheongho Han
A microlensing lensing zone refers to the range of planet-star separations where the probability of detecting a planetary signal is high. Its conventional definition as the range b…
KMT-2018-BLG-1988Lb: microlensing super-Earth orbiting a low-mass disk dwarf
Cheongho Han, Andrew Gould, Michael D. Albrow +20
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 t…
OGLE-2015-BLG-1670Lb: A Cold Neptune beyond the Snow Line in the Provisional WFIRST Microlensing Survey Field
Clément Ranc, David P. Bennett, Yuki Hirao +56
We present the analysis of the microlensing event OGLE-2015-BLG-1670, detected in a high-extinction field, very close to the Galactic plane. Due to the dust extinction along the li…
KMT-2018-BLG-1743: Planetary Microlensing Event Occurring on Two Source Stars
Cheongho Han, Michael D. Albrow, Sun-Ju Chung +18
We present the analysis of the microlensing event KMT-2018-BLG-1743. The light curve of the event, with a peak magnification , exhibits two anomaly features,…
OGLE-2017-BLG-0448Lb: A Low Mass-Ratio Wide-Orbit Microlensing Planet?
Ruocheng Zhai, RadosÅaw Poleski, Weicheng Zang +38
The gravitational microlensing technique is most sensitive to planets in a Jupiter-like orbit and has detected more than 200 planets. However, only a few wide-orbit () micro…
OGLE-2019-BLG-1180Lb: Discovery of a Wide-orbit Jupiter-mass Planet around a Late-type Star
Sun-Ju Chung, Andrzej Udalski, Jennifer C. Yee +30
We report on the discovery and analysis of the planetary microlensing event OGLE-2019-BLG-1180 with a planet-to-star mass ratio . The event OGLE-2019-BLG-1180 has una…
KMT-2017-BLG-2820 and the Nature of the Free-Floating Planet Population
Yoon-Hyun Ryu, Przemek Mróz, Andrew Gould +28
We report a new free-floating planet (FFP) candidate, KMT-2017-BLG-2820, with Einstein radius $θ_\e\simeq 6\,\muas$, lens-source relative proper motion $μ_\rel \simeq 8\,\masyr$,…
The Korea Microlensing Telescope Network (KMTNet) Alert Algorithm and Alert System
Hyoun-Woo Kim, Kyu-Ha Hwang, Yossi Shvartzvald +17
We describe a new microlensing-event alert algorithm that is tailored to the Korea Microlensing Telescope Network (KMTNet) multi-observatory system. The algorithm focuses on detect…
KMT-2019-BLG-0842Lb: A Cold Planet Below the Uranus/Sun Mass Ratio
Youn Kil Jung, Andrzej Udalski, Weicheng Zang +59
We report the discovery of a cold planet with a very low planet/host mass ratio of , which is similar to the ratio of Uranus/Sun ($q=4.37 \times 10^…
Astrometric Properties of Gravitational Binary-Microlens Events and Their Applications
Cheongho Han, Mun-Suk Chun, Kyongae Chang
In this paper, we study the astrometric properties of gravitational microlensing events caused by binary lenses. By investigating the centroid shifts for various types of binary-le…
Mass Production of 2023 KMTNet Microlensing Planets. III: Three Planets from the Subprime Field
Hongyu Li, Zhixing Li, Weicheng Zang +56
To complete the analysis of the 2023 KMTNet subprime-field microlensing planetary events identified by its AlertFinder system, we present the analysis of six events, KMT-2023-BLG-(…
KMT-2016-BLG-1836Lb: A Super-Jovian Planet From A High-Cadence Microlensing Field
Hongjing Yang, Xiangyu Zhang, Kyu-Ha Hwang +24
We report the discovery of a super-Jovian planet in the microlensing event KMT-2016-BLG-1836, which was found by the Korea Microlensing Telescope Network's high-cadence observation…
Spectroscopic Mass and Host-star Metallicity Measurements for Newly Discovered Microlensing Planet OGLE-2018-BLG-0740Lb
Cheongho Han, Jennifer C. Yee, Andrzej Udalski +63
We report the discovery of the microlensing planet OGLE-2018-BLG-0740Lb. The planet is detected with a very strong signal of , but the interpretation of the signal…
Probing the Spatial Distribution of Extrasolar Planets with Gravitational Microlensing
Cheongho Han, Young Woon Kang
Under the current microlensing planet search strategy of monitoring events caused by stellar-mass lenses, only planets located within a narrow region of separations from central st…
KMT-2024-BLG-1044L: A sub-Uranus microlensing planet around a host at the star-brown dwarf mass boundary
Cheongho Han, Yoon-Hyun Ryu, Chung-Uk Lee +14
We analysed microlensing data to uncover the nature of the anomaly that appeared near the peak of the short-timescale microlensing event KMT-2024-BLG-1044. Despite the anomaly's br…
KMT-2023-BLG-1431Lb: A New Microlensing Planet from a Subtle Signature
Aislyn Bell, Jiyuan Zhang, Youn Kil Jung +70
The current studies of microlensing planets are limited by small number statistics. Follow-up observations of high-magnification microlensing events can efficiently form a statisti…
OGLE-2018-BLG-0799Lb: a Planet with Spitzer Parallax
Weicheng Zang, Yossi Shvartzvald, Andrzej Udalski +73
We report the discovery and analysis of a planet in the microlensing event OGLE-2018-BLG-0799. The planetary signal was observed by several ground-based telescopes, and the planet-…
KMT-2019-BLG-0797: binary-lensing event occurring on a binary stellar system
Cheongho Han, Chung-Uk Lee, Yoon-Hyun Ryu +18
We analyze the microlensing event KMT-2019-BLG-0797. The light curve of the event exhibits two anomalous features from a single-lens single-source model, and we aim to reveal the n…
The Effect of Luminous Lens Blending in Gravitational Microlensing Experiments
Seunghun Lee, Cheongho Han
The most important uncertainty in the results of gravitational microlensing experiments comes from the difficulties of photometry caused by blending of source stars. Recently Nemir…
OGLE-2019-BLG-1470LABc: Another Microlensing Giant Planet in a Binary System?
Renkun Kuang, Weicheng Zang, Youn Kil Jung +36
We report the discovery and analysis of a candidate triple-lens single-source (3L1S) microlensing event, OGLE-2019-BLG-1470. This event was first classified as a normal binary-lens…
Angular Radii of Stars via Microlensing
B. Scott Gaudi, David S. Graff, Cheongho Han
We outline a method by which the angular radii of giant and main sequence stars in the Galactic bulge can be measured to a few percent accuracy. The method combines ground-based ph…
Systematic KMTNet Planetary Anomaly Search. IV. Complete Sample of 2019 Prime-Field
Weicheng Zang, Hongjing Yang, Cheongho Han +33
We report the complete statistical planetary sample from the prime fields () of the 2019 Korea Microlensing Telescope Network (KMTNet) microlensing survey.…
Systematic KMTNet Planetary Anomaly Search. VIII. Complete Sample of 2019 Subprime Field Planets
Youn Kil Jung, Weicheng Zang, Hanyue Wang +41
We complete the publication of all microlensing planets (and ``possible planets'') identified by the uniform approach of the KMT AnomalyFinder system in the 21 KMT subprime fields…
MOA-2022-BLG-033Lb, KMT-2023-BLG-0119Lb, and KMT-2023-BLG-1896Lb: Three low mass-ratio microlensing planets detected through dip signals
Cheongho Han, Ian A. Bond, Youn Kil Jung +45
We examined the anomalies in the light curves of the lensing events MOA-2022-BLG-033, KMT-2023-BLG-0119, and KMT-2023-BLG-1896. We conducted detailed modeling of the light curves t…
Direct Lens Imaging of Galactic Bulge Microlensing Events
Cheongho Han, Heon-Young Chang
Recently, from the Hubble Space Telescope (HST) images of one of the Large Magellanic Cloud (LMC) events taken 6.3 years after the original lensing measurement, Alcock et al. were…
The Many Possible Interpretations of Microlensing Event OGLE-2002-BLG-055
B. Scott Gaudi, Cheongho Han
Microlensing event OGLE-2002-BLG-055 is characterized by a smooth, slightly asymmetric single-lens curve with an isolated, secure data point that is ~0.6 magnitudes brighter than n…
Probable brown dwarf companions detected in binary microlensing events during the 2018-2020 seasons of the KMTNet survey
Cheongho Han, Youn Kil Jung, Doeon Kim +48
We inspect the microlensing data of the KMTNet survey collected during the 2018--2020 seasons in order to find lensing events produced by binaries with brown-dwarf companions. In o…
KMT-2022-BLG-0086: Another binary-lens binary-source microlensing event
Sun-Ju Chung, Kyu-Ha Hwang, Jennifer C. Yee +40
We present the analysis of a microlensing event KMT-2022-BLG-0086 of which the overall light curve is not described by a binary-lens single-source (2L1S) model, which suggests the…
Systematic KMTNet Planetary Anomaly Search. VI. Complete Sample of 2018 Sub-Prime-Field Planets
Youn Kil Jung, Weicheng Zang, Cheongho Han +29
We complete the analysis of all 2018 sub-prime-field microlensing planets identified by the KMTNet AnomalyFinder. Among the 9 previously unpublished events with clear planetary sol…
Properties of Density and Velocity Gaps Induced by a Planet in a Protoplanetary Disk
Han Gyeol Yun, Woong-Tae Kim, Jaehan Bae +1
Gravitational interactions between a protoplanetary disk and its embedded planet is one of the formation mechanisms of gaps and rings found in recent ALMA observations. To quantify…
Four Microlensing Planets with Faint-source Stars Identified in the 2016 and 2017 Season Data
Cheongho Han, Andrzej Udalski, Doeon Kim +32
Microlensing planets occurring on faint source stars can escape detection due to their weak signals. Occasionally, detections of such planets are not reported due to the difficulty…
KMT-2018-BLG-0748Lb: Sub-Saturn Microlensing Planet Orbiting an Ultracool Host
Cheongho Han, In-Gu Shin, Youn Kil Jung +18
We announce the discovery of a microlensing planetary system, in which a sub-Saturn planet is orbiting an ultracool dwarf host. We detect the planetary system by analyzing the shor…
KMT-2019-BLG-0371 and the Limits of Bayesian Analysis
Yun Hak Kim, Sun-Ju Chung, Jennifer C. Yee +54
We show that the perturbation at the peak of the light curve of microlensing event KMT-2019-BLG-0371 is explained by a model with a mass ratio between the host star and planet of $…
OGLE-2017-BLG-1186: first application of asteroseismology and Gaussian processes to microlensing
Shun-Sheng Li, Weicheng Zang, Andrzej Udalski +102
We present the analysis of the event OGLE-2017-BLG-1186 from the 2017 Spitzer microlensing campaign. This is a remarkable microlensing event because its source is photometrically b…
Optimal Survey Strategies and Predicted Planet Yields for the Korean Microlensing Telescope Network
Calen B. Henderson, B. Scott Gaudi, Cheongho Han +4
The Korean Microlensing Telescope Network (KMTNet) will consist of three 1.6m telescopes each with a 4 deg^{2} field of view (FoV) and will be dedicated to monitoring the Galactic…
Systematic KMTNet Planetary Anomaly Search. IX. Complete Sample of 2016 Prime-Field Planets
In-Gu Shin, Jennifer C. Yee, Weicheng Zang +58
As a part of the ``Systematic KMTNet Planetary Anomaly Search" series, we report five new planets (namely, OGLE-2016-BLG-1635Lb, MOA-2016-BLG-532Lb, KMT-2016-BLG-0625Lb, OGLE-2016-…
Mass Production of 2023 KMTNet Microlensing Planets I: Low Mass Ratio
Yoon-Hyun Ryu, Andrzej Udalski, Hongjing Yang +34
We initiate the systematic search for planets in the 2023 data of the Korea Microlensing Telescope Network (KMTNet), focusing on those planets found by the KMTNet AnomalyFinder wit…
Analysis of Microlensing Light Curves Induced by Multiple-Planet Systems
Cheongho Han
To maximize the number of planet detections by increasing efficiency, current microlensing follow-up observation experiments are focusing on high-magnification events to search for…
Lunar Occultation of MACHOs
Cheongho Han, Vijay K. Narayanan, Andrew Gould
Lunar occultation can be used to measure the proper motions of some of the long time scale microlensing events, $t_{e} \gsim 70$ days, now being detected toward the Galactic bulge.…
Improved period variations of 32 contact binaries with rapidly decreasing periods in the Galactic Bulge
Kyeongsoo Hong, Jae Woo Lee, Dong-Jin Kim +4
We present detailed analyses of updated eclipse timing diagrams for 32 contact binary merger candidates in the Galactic bulge. The photometric data was obtained from 2016 to 2021 u…
Unique Determination of the Physical Parameters of Individual MACHOs from Astrometric Parallax Measurements
Cheongho Han
The Einstein time scale, which is the only information obtained from current microlensing experiments, results from a complicated combination of the lens parameters that we want to…