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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…
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…
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…
OGLE-2015-BLG-0845L: A low-mass M dwarf from the microlensing parallax and xallarap effects
Zhecheng Hu, Wei Zhu, Andrew Gould +51
We present the analysis of the microlensing event OGLE-2015-BLG-0845, which was affected by both the microlensing parallax and xallarap effects. The former was detected via the sim…
Brown dwarf companions in binaries detected from the 2021 season high-cadence microlensing surveys
Cheongho Han, Youn Kil Jung, Ian A. Bond +45
As a part of the project aiming to build a homogeneous sample of binary-lens (2L1S) events containing brown-dwarf (BD) companions, we investigate the 2021 season microlensing data…
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…
Brown-dwarf companions in microlensing binaries detected during the 2016--2018 seasons
Cheongho Han, Yoon-Hyun Ryu, In-Gu Shin +60
With the aim of finding microlensing binaries containing brown-dwarf (BD) companions, we investigate the microlensing survey data collected during the 2016--2018 seasons. For this…
Proton Penetration Efficiency over a High Altitude Observatory in Mexico
S. Miyake, T. Koi, Y. Muraki +12
In association with a large solar flare on November 7, 2004, the solar neutron detectors located at Mt. Chacaltaya (5,250m) in Bolivia and Mt. Sierra Negra (4,600m) in Mexico recor…
Precision measurement of a brown dwarf mass in a binary system in the microlensing event OGLE-2019-BLG-0033/MOA-2019-BLG-035
A. Herald, A. Udalski, V. Bozza +89
Context. Brown dwarfs are poorly understood transition objects between stars and planets, with several competing mechanisms having been proposed for their formation. Mass measureme…
Solar Neutron Decay Protons observed in November 7, 2004
Yasushi Muraki, Jose F. Valde-Galicia, Ernesto Ortiz +10
We have found an interesting event registered by the solar neutron telescopes installed at high mountains in Bolivia (5250 m a.s.l.) and Mexico (4600 m a.s.l.). The event was obser…
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…
Candidate Brown-dwarf Microlensing Events with Very Short Timescales and Small Angular Einstein Radii
Cheongho Han, Chung-Uk Lee, Andrzej Udalski +62
Short-timescale microlensing events are likely to be produced by substellar brown dwarfs (BDs), but it is difficult to securely identify BD lenses based on only event timescales $t…
Spitzer Microlensing parallax reveals two isolated stars in the Galactic bulge
Weicheng Zang, Yossi Shvartzvald, Tianshu Wang +90
We report the mass and distance measurements of two single-lens events from the 2017 Spitzer microlensing campaign. The ground-based observations yield the detection of finite-sour…
OGLE-2018-BLG-0022: First Prediction of an Astrometric Microlensing Signal from a Photometric Microlensing Event
Cheongho Han, Ian A. Bond, Andrzej Udalski +63
In this work, we present the analysis of the binary microlensing event OGLE-2018-BLG-0022 that is detected toward the Galactic bulge field. The dense and continuous coverage with t…
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…
Spitzer Microlensing of MOA-2016-BLG-231L : A Counter-Rotating Brown Dwarf Binary in the Galactic Disk
Sun-Ju Chung, Andrew Gould, Jan Skowron +60
We analyze the binary microlensing event MOA-2016-BLG-231, which was observed from the ground and from Spitzer. The lens is composed of very low-mass brown dwarfs (BDs) with $M_1 =…
OGLE-2016-BLG-0156: Microlensing Event With Pronounced Microlens-Parallax Effects Yielding Precise Lens Mass Measurement
Youn Kil Jung, Cheongho Han, Ian A. Bond +53
We analyze the gravitational binary-lensing event OGLE-2016-BLG-0156, for which the lensing light curve displays pronounced deviations induced by microlens-parallax effects. The li…
OGLE-2017-BLG-0039: Microlensing Event with Light from the Lens Identified from Mass Measurement
C. Han, Y. K. Jung, A. Udalski +58
We present the analysis of the caustic-crossing binary microlensing event OGLE-2017-BLG-0039. Thanks to the very long duration of the event, with an event time scale $t_{\rm E}\sim…
OGLE-2014-BLG-0962 and the First Statistical Validation of Bayesian Priors for Galactic Microlensing
Yutong Shan, Jennifer C. Yee, Andrzej Udalski +46
OGLE-2014-BLG-0962 (OB140962) is a stellar binary microlensing event that was well-covered by observations from the Spitzer satellite as well as ground-based surveys. Modelling yie…
A study of light travel time effect in short-period MOA eclipsing binaries via eclipse timing
M. C. A. Li, N. J. Rattenbury, I. A. Bond +23
A sample of 542 eclipsing binaries (EBs) with periods shorter than 2 d were selected from the Microlensing Observations in Astrophysics (MOA) EB catalogue (Li et al. 2017) for ecli…
OGLE-2016-BLG-1469L: Microlensing Binary Composed of Brown Dwarfs
C. Han, A. Udalski, T. Sumi +50
We report the discovery of a binary composed of two brown dwarfs, based on the analysis of the microlensing event OGLE-2016-BLG-1469. Thanks to detection of both finite-source and…
OGLE-2016-BLG-1003: First Resolved Caustic-crossing Binary-source Event Discovered by Second-generation Microlensing Surveys
Y. K. Jung, A. Udalski, I. A. Bond +50
We report the analysis of the first resolved caustic-crossing binary-source microlensing event OGLE-2016-BLG-1003. The event is densely covered by the round-the-clock observations…
Binary Source Microlensing Event OGLE-2016-BLG-0733: Interpretation of A Long-term Asymmetric Perturbation
Y. K. Jung, A. Udalski, J. C. Yee +50
In the process of analyzing an observed light curve, one often confronts various scenarios that can mimic the planetary signals causing difficulties in the accurate interpretation…
Simultaneous Observation of Solar Neutrons from the ISS and High Mountain Observatories in association with a flare on July 8, 2014
Y. Muraki, D. Lopez, K. Koga +17
An M6.5-class flare was observed at N12E56 of the solar surface at 16:06 UT on July 8, 2014. In association with this flare, solar neutron detectors located on two high mountains,…