{
  "abstract": "We present an analysis of two planetary microlensing events, KMT-2021-BLG-0247 and MOA-2023-BLG-169, both of which exhibit high magnifications and low planet--host mass ratios, but with markedly different levels of parameter constraint. For KMT-2021-BLG-0247, the finite-source effect and microlens parallax are both clearly detected, leading to unusually tight constraints on the physical properties of the lens system. The host mass and lens distance are approximately $M_{\\rm L}=0.9\\pm0.1\\,M_\\odot$ and $D_{\\rm L}=6.7^{+1.0}_{-0.3}\\,\\mathrm{kpc}$, respectively, and the planet mass is $M_{\\rm p}=41\\pm5\\,M_\\oplus$. The projected planet--host separations are $a_\\perp=3.4^{+0.7}_{-0.3}\\,\\mathrm{au}$ and $3.0^{+0.6}_{-0.3}\\,\\mathrm{au}$ for the wide and close solutions, respectively. In contrast, MOA-2023-BLG-169 involves an extremely faint source, with $I_{S,{\\rm OGLE}}=26.73$, such that the light curve permits a broad family of strongly correlated solutions. We therefore construct the physical-parameter likelihood using approximate invariant combinations of the light-curve parameters and supplement it with post-event Euclid/VIS imaging from the Euclid Q2 Galactic Bulge Survey (Beaulieu et al. 2026). The Euclid data reveal a component at the event position with ${\\rm VIS}_{\\rm AB}=23.05\\pm0.09\\,{\\rm mag}$. Interpreting this component as the combined light from the source and any luminous lens, the resulting posterior gives $M_{\\rm L}=0.48^{+0.23}_{-0.17}\\,M_\\odot$, $D_{\\rm L}=3.50^{+2.82}_{-1.20}\\,\\mathrm{kpc}$, $a_\\perp=1.62^{+0.77}_{-0.43}\\,\\mathrm{au}$, and $M_{\\rm p}=143^{+103}_{-63}\\,M_\\oplus$. MOA-2023-BLG-169 demonstrates that, for an extreme faint-source event, even the event timescale and angular Einstein radius can remain strongly dependent on the Galactic prior and independent flux constraints.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.10308",
  "author_total": 59,
  "authors": [
    {
      "name": "Kansuke Nunota"
    },
    {
      "name": "Andrew Gould"
    },
    {
      "name": "Takahiro Sumi"
    },
    {
      "name": "Ian A. Bond"
    },
    {
      "name": "Jennifer C. Yee"
    },
    {
      "name": "Valerio Bozza"
    },
    {
      "name": "Fumio Abe"
    },
    {
      "name": "David P. Bennett"
    },
    {
      "name": "Aparna Bhattacharya"
    },
    {
      "name": "Kotaro Daimon"
    },
    {
      "name": "Ryusei Hamada"
    },
    {
      "name": "Yuki Hirao"
    },
    {
      "name": "Takuto Inoue"
    },
    {
      "name": "Stela Ishitani Silva"
    },
    {
      "name": "Shuma Makida"
    },
    {
      "name": "Shota Miyazaki"
    },
    {
      "name": "Yasushi Muraki"
    },
    {
      "name": "Seiya Nakayama"
    },
    {
      "name": "Ryo Ogawa"
    },
    {
      "name": "Ryunosuke Oishi"
    },
    {
      "name": "Greg Olmschenk"
    },
    {
      "name": "Hideaki Ose"
    },
    {
      "name": "Clément Ranc"
    },
    {
      "name": "Nicholas J. Rattenbury"
    },
    {
      "name": "Yuki K. Satoh"
    },
    {
      "name": "Daisuke Suzuki"
    },
    {
      "name": "Takuto Tamaoki"
    },
    {
      "name": "Sean K. Terry"
    },
    {
      "name": "Paul J. Tristram"
    },
    {
      "name": "Chihiro Ueda"
    },
    {
      "name": "Aikaterini Vandorou"
    },
    {
      "name": "Hibiki Yama"
    },
    {
      "name": "Michael D. Albrow"
    },
    {
      "name": "Sun-Ju Chung"
    },
    {
      "name": "Cheongho Han"
    },
    {
      "name": "Kyu-Ha Hwang"
    },
    {
      "name": "Youn Kil Jung"
    },
    {
      "name": "Yoon-Hyun Ryu"
    },
    {
      "name": "In-Gu Shin"
    },
    {
      "name": "Yossi Shvartzvald"
    },
    {
      "name": "Hongjing Yang"
    },
    {
      "name": "Weicheng Zang"
    },
    {
      "name": "Dong-Jin Kim"
    },
    {
      "name": "Chung-Uk Lee"
    },
    {
      "name": "Byeong-Gon Park"
    },
    {
      "name": "Andrzej Udalski"
    },
    {
      "name": "Przemek Mróz"
    },
    {
      "name": "Radosław Poleski"
    },
    {
      "name": "Jan Skowron"
    },
    {
      "name": "Michał K. Szymański"
    },
    {
      "name": "Igor Soszyński"
    },
    {
      "name": "Paweł Pietrukowicz"
    },
    {
      "name": "Szymon Kozłowski"
    },
    {
      "name": "Krzysztof Ulaczyk"
    },
    {
      "name": "Krzysztof A. Rybicki"
    },
    {
      "name": "Patryk Iwanek"
    },
    {
      "name": "Marcin Wrona"
    },
    {
      "name": "Mariusz Gromadzki"
    },
    {
      "name": "Mateusz J. Mróz"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/7eg138zr3870s.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.10308",
  "fulltext_url": null,
  "id": "7eg138zr3870s",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.10308",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.EP"
    ],
    [
      "arxiv",
      "astro-ph.GA"
    ],
    [
      "openalex",
      "3103|Stellar, planetary, and galactic studies"
    ]
  ],
  "openalex": "W7221039993",
  "pdf_url": "https://arxiv.org/pdf/2610.10308",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-08",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/7eg138zr3870s.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:27:54Z",
      "native_id": "2610.10308",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.10308"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.EP",
      "subfield": "planetary"
    }
  ],
  "title": "Two Low-Mass-Ratio Microlensing Planets from High-Magnification Events: KMT-2021-BLG-0247 and MOA-2023-BLG-169",
  "title_text": "Two Low-Mass-Ratio Microlensing Planets from High-Magnification Events: KMT-2021-BLG-0247 and MOA-2023-BLG-169",
  "type": "preprint",
  "updated_at": "2026-10-30T12:27:54Z",
  "url": "https://research.draconitic.com/paper/7eg138zr3870s",
  "venue": "arXiv",
  "versions": []
}