{
  "abstract": "Direct imaging and characterization of rocky exoplanets remains one of the central challenges in exoplanetary science. The mid-infrared (mid-IR) offers a favorable high-contrast imaging (HCI) regime, as the planet-star contrast is more moderate than at shorter wavelengths. However, mid-IR observations with extremely large ground-based telescopes (ELTs) are strongly affected by spatio-temporal fluctuations in atmospheric water vapor (WV), which introduce chromatic wavefront errors that are largely invisible to adaptive optics systems operating at shorter wavelengths. This poses a significant challenge for mid-IR HCI instruments such as METIS, which aims to detect thermal emission from rocky exoplanets in the $N$-band (8--13 $μ$ m). To quantify WV-induced wavefront errors, we analyze $K$-band fringe-tracker data from the GRAVITY instrument at the VLTI and derive the optical path difference between group-delay and phase-delay measurements. This difference provides a direct measure of the differential WV column density ($Σ$) above the telescopes. We examine the dependence of the RMS differential WV column density ($σ_Σ$) on precipitable water vapor (PWV), airmass, seeing, and wind speed across multiple VLTI configurations. Among these parameters, PWV shows the strongest correlation with $σ_Σ$. We further explore the influence of the vertical PWV distribution on this relationship. Next, we use power-spectral-density analysis to quantify how increasing PWV modulates $Σ$ variability. The wavefront error associated with this phenomenon on ELT scale is approximately 15~nm RMS in the $L$-band and 175~nm RMS in the $N$-band, relative to the $K$-band. These results provide a quantitative framework for assessing and mitigating atmospheric WV effects in next-generation mid-IR HCI instruments.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.14801",
  "author_total": 10,
  "authors": [
    {
      "name": "Abhirami S Raghu"
    },
    {
      "name": "Prashant Pathak"
    },
    {
      "name": "Olivier Absil"
    },
    {
      "name": "Benjamin Courtney-Barrer"
    },
    {
      "name": "Gilles Orban de Xivry"
    },
    {
      "name": "Julien Woillez"
    },
    {
      "name": "Alexis Matter"
    },
    {
      "name": "Philippe Bério"
    },
    {
      "name": "Roy van Boekel"
    },
    {
      "name": "Bernhard Brandl"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/7dyhb1wxjp8z2.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.14801",
  "fulltext_url": null,
  "id": "7dyhb1wxjp8z2",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.14801",
  "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.IM"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2610.14801",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-10",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/7dyhb1wxjp8z2.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:29:06Z",
      "native_id": "2610.14801",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.14801"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.IM",
      "subfield": "instrumentation-methods"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.EP",
      "subfield": "planetary"
    }
  ],
  "title": "Mid-IR Water-Vapor Seeing: Implications for ELT/METIS High-Contrast Imaging from VLTI Data",
  "title_text": "Mid-IR Water-Vapor Seeing: Implications for ELT/METIS High-Contrast Imaging from VLTI Data",
  "type": "preprint",
  "updated_at": "2026-10-30T12:29:06Z",
  "url": "https://research.draconitic.com/paper/7dyhb1wxjp8z2",
  "venue": "arXiv",
  "versions": [
    {
      "doi": "10.1093/rasti/rzag075",
      "pid": null,
      "relation": "published-as",
      "title": null,
      "venue": null
    }
  ]
}