{
  "abstract": "Precision stellar astrometry near the Sun can constrain the parametrized post-Newtonian (PPN) parameter gamma through gravitational light deflection. This study develops ECLIPSE-X, a localized multi-frame estimation architecture in which one persistent relativistic parameter is estimated simultaneously with frame-dependent spacecraft line-of-sight and roll states, separated by their differing spatial signatures and by the persistence of gamma across frames. The aim is not a competitive determination of gamma, but an assessment of whether such a joint solution and its formal covariance stay statistically valid under realistic astrometric model error. A synthetic field of 250 stars spanning 1.22-8 apparent solar radii is observed over 40 frames at 5-s cadence; weighted least squares estimates gamma with three navigation states per frame, and Schur-complement marginalization gives the formal uncertainty in gamma after navigation coupling. The nominal solution recovers gamma = 1.0001198167 with sigma_gamma = 3.075104e-4, and a 1000-realization ensemble confirms calibration. Perturbations unknown to the estimator identify plate-scale mismatch as the dominant failure mechanism: a 300-ppm scale error alone inflates the empirical-to-formal uncertainty ratio to 7126.6 with zero 1-sigma and 2-sigma coverage, against 2.18 for catalog-coordinate mismatch and 1.12 for a frame-coherent radial perturbation, while every realization converges numerically: convergence does not guarantee statistical validity. Augmenting the state with a plate-scale parameter restores consistency, at a fixed 21.2% cost in the precision of gamma set by the correlation between the two persistent parameters. A calibration sweep shows the unaugmented estimator is covariance-consistent only below sigma_p = 2.7884e-8, so the augmented state is a requirement, not a refinement, for near-Sun relativistic astrometric estimators.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.36514",
  "author_total": 1,
  "authors": [
    {
      "name": "Pedro J. Llanos"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/6k1rxg4y3xz73.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.36514",
  "fulltext_url": null,
  "id": "6k1rxg4y3xz73",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.36514",
  "language": null,
  "licence": "LicenseRef-arXiv-nonexclusive-1.0",
  "licence_label": "arXiv licence",
  "licence_source": "article",
  "licence_url": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.IM"
    ],
    [
      "arxiv",
      "gr-qc"
    ],
    [
      "openalex",
      "3103|Stellar, planetary, and galactic studies"
    ]
  ],
  "openalex": "W7214989914",
  "pdf_url": "https://arxiv.org/pdf/2609.36514",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-29",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/6k1rxg4y3xz73.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:25:31Z",
      "native_id": "2609.36514",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.36514"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.IM",
      "subfield": "instrumentation-methods"
    },
    {
      "field": "physics",
      "origin": "arxiv:gr-qc",
      "subfield": "gravitation"
    }
  ],
  "title": "ECLIPSE-X: Plate-Scale Calibration as the Binding Constraint on Relativistic Astrometry with Spacecraft Navigation",
  "title_text": "ECLIPSE-X: Plate-Scale Calibration as the Binding Constraint on Relativistic Astrometry with Spacecraft Navigation",
  "type": "preprint",
  "updated_at": "2026-10-30T12:25:31Z",
  "url": "https://research.draconitic.com/paper/6k1rxg4y3xz73",
  "venue": "arXiv",
  "versions": []
}