{
  "abstract": "This paper presents a precise eclipse-timing analysis of TIC 259864042 (= EC 02406--6408, Gaia DR3 4647004122914240640) using eleven sectors of TESS photometry spanning 2018--2025 (7.1 yr). The system exhibits a single deep eclipse with a V-shaped profile at phase 0 and no detectable counterpart at phase 0.5. Four independent period-search methods converge to a common period agreeing to within 7 parts per million. An independent reduction with the SHERLOCK pipeline, using its own 120-second TESS photometry, confirms the same period at the same precision. A joint linear ephemeris fit gives P = 0.46048676 $\\pm$ 0.0000001 d (11.059 h) and T_0 = 2458325.70381 $\\pm$ 0.00002 BJD, with a residual RMS of 0.87 min across the 7.1-yr baseline. Per-sector ephemeris fits show residual medians within $\\pm$0.42 min of zero, confirming that no cycle slip has occurred across the large TESS data gaps. The period is stable at the level of $Δ$BIC = +5.21 (in favour of the constant-period model); an upper limit of $|\\dot{P}| \\le 1 \\times 10^{-9}$ d d$^{-1}$ is placed on any secular period change. A PHOEBE 2.4 fit to the Sector 27 light curve yields $i = 80.8^{\\circ} \\pm 0.5^{\\circ}$, $R_1 = 0.21 \\pm 0.01\\ R_{\\odot}$, $R_2 = 0.25 \\pm 0.02\\ R_{\\odot}$, $q = 0.49 \\pm 0.07$, consistent with a grazing detached geometry and a mid-M-dwarf companion. The TESS light curve alone cannot distinguish between the two temperatures 25100 K and 31000 K. The paper discusses the system in the context of the sdB eclipsing binary population, and notes that while the current data are consistent with a short-period sdB+M-dwarf architecture, a phase-resolved spectrum is needed to independently confirm the sdB identification.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.31076",
  "author_total": 1,
  "authors": [
    {
      "name": "Rana Khan"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/d4wz36ycpexsz.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.31076",
  "fulltext_url": null,
  "id": "d4wz36ycpexsz",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.31076",
  "language": null,
  "licence": "CC0-1.0",
  "licence_label": "CC0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/publicdomain/zero/1.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.SR"
    ],
    [
      "openalex",
      "3103|Stellar, planetary, and galactic studies"
    ]
  ],
  "openalex": "W7223381120",
  "pdf_url": "https://arxiv.org/pdf/2610.31076",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-22",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/d4wz36ycpexsz.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:34:34Z",
      "native_id": "2610.31076",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.31076"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.SR",
      "subfield": "stellar"
    }
  ],
  "title": "A precise TESS ephemeris for the short-period binary TIC-259864042",
  "title_text": "A precise TESS ephemeris for the short-period binary TIC-259864042",
  "type": "preprint",
  "updated_at": "2026-10-30T12:34:34Z",
  "url": "https://research.draconitic.com/paper/d4wz36ycpexsz",
  "venue": "arXiv",
  "versions": []
}