{
  "abstract": "We report the first proper motion and acceleration measurements of the infrared (IR) counterpart to Sagittarius A* (Sgr A*-IR), the supermassive black hole (SMBH) at the center of our Galaxy, in the Gaia-Celestial Reference Frame (Gaia-CRF3). This reference frame realizes the International Celestial Reference System (ICRS), which is an absolute reference coordinate system defined by quasars. A combination of Gaia and Hubble Space Telescope data was used to transform Keck adaptive optics (AO) observations into Gaia-CRF3. We developed a method for selecting reference stars that minimizes astrometric transformation errors (statistical error = $0.10-0.63$ mas) and drift of the coordinate system (systematic error $\\sim 0.01$ mas/yr). We find the proper motion of Sgr A*-IR in Gaia-CRF3 to be $μ_{α^{*}} = -3.093 \\pm 0.085$ mas yr$^{-1}$ and $μ_δ= -5.62 \\pm 0.13$ mas yr$^{-1}$ with the initial position at $t_{0} = 2016.0$ of R.A. = 266.41680848 $\\pm$ 0.00000029 deg and DEC = -29.00783947 $\\pm$ 0.00000050 deg, which translates to a precision of 1.05 mas in R.A. and 1.79 mas DEC. This is consistent with the astrometric measurements of the radio counterpart to Sgr A* by \\citet{Xu_2022}. We also place a $2σ$ upper constraint of the acceleration of Sgr A*-IR on the sky at 0.061 mas yr$^{-2}$. This acceleration limit on Sgr A*-IR excludes any intermediate-mass black hole companion with mass $\\gtrsim 4\\times 10^{4}$ $M_{\\odot}$ within a distance of $\\sim$0.01 pc, consistent with previous studies. With the release of Gaia Data Release 4, we predict these limits will be improved by at least a factor of two.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.04077",
  "author_total": 12,
  "authors": [
    {
      "name": "Rebecca A. Lewis-Merrill"
    },
    {
      "name": "Tuan Do"
    },
    {
      "name": "Matthew W. Hosek Jr."
    },
    {
      "name": "Gregory David Martinez"
    },
    {
      "name": "Shoko Sakai"
    },
    {
      "name": "Kelly Kosmo O'Neil"
    },
    {
      "name": "Grant Weldon"
    },
    {
      "name": "Abhimat Gautam"
    },
    {
      "name": "Zoë Haggard"
    },
    {
      "name": "Andrea M. Ghez"
    },
    {
      "name": "Jessica R. Lu"
    },
    {
      "name": "Keith Matthews"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/3yrqjqs2nkgn5.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.04077",
  "fulltext_url": null,
  "id": "3yrqjqs2nkgn5",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.04077",
  "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.GA"
    ],
    [
      "arxiv",
      "astro-ph.IM"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2609.04077",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-03",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/3yrqjqs2nkgn5.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:18:31Z",
      "native_id": "2609.04077",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.04077"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.IM",
      "subfield": "instrumentation-methods"
    }
  ],
  "title": "Absolute Motion of the Infrared Counterpart to Sagittarius A* in the Gaia Celestial Reference Frame 3 and Limits on an Intermediate-mass Black Hole Companion",
  "title_text": "Absolute Motion of the Infrared Counterpart to Sagittarius A* in the Gaia Celestial Reference Frame 3 and Limits on an Intermediate-mass Black Hole Companion",
  "type": "preprint",
  "updated_at": "2026-10-30T12:18:31Z",
  "url": "https://research.draconitic.com/paper/3yrqjqs2nkgn5",
  "venue": "arXiv",
  "versions": []
}