{
  "abstract": "Submillimeter very long baseline interferometry (VLBI) achieves higher angular resolution and probes more optically thin emission near supermassive black holes, with less interstellar scattering toward Sgr A$^*$. Above 345 GHz, however, the atmosphere confines ground-based VLBI to a few high, dry sites. Using 2012-2022 weather, we forecast what a 2.5 m telescope floating at 35-40 km, a successor to the 22 GHz Balloon-borne VLBI Experiment (BVEX) pathfinder, would add to ground-VLBI arrays at 345-690 GHz. The balloon adds little baseline length but reaches higher frequencies, where a fixed baseline is longer in wavelengths. On an ALMA-balloon baseline, Sgr A$^*$ at 460 GHz is at the detection threshold, with ten or more 20 s detections on about half of the simulated April days. These detections lie beyond the polarimetric photon ring transition, where the $n=1$ ring dominates the polarized visibility amplitudes. M87$^*$ at 460 GHz would need frequency phase transfer from a 230 GHz reference to be detected. With phase transfer, most Sgr A$^*$ detections beyond the transition at 460 GHz are on balloon baselines, whose thermal noise meets the linear-polarization threshold within one 300 s scan. At 690 GHz such detections require phase transfer that stays coherent at three times the reference frequency. In Fisher forecasts, a 460 GHz ring-geometry constraint requires balloons but is weaker than at 345 GHz, where balloons add little improvement. High-resolution 460 GHz VLBI science would require a 32 GHz bandwidth backend, submillimeter receivers, and simultaneous 230 GHz reference recording at every station.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.24396",
  "author_total": 5,
  "authors": [
    {
      "name": "Mayukh Bagchi"
    },
    {
      "name": "Dominic W. Pesce"
    },
    {
      "name": "Felix M. Thiel"
    },
    {
      "name": "Laura M. Fissel"
    },
    {
      "name": "Lindy Blackburn"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/98tcb4gwm6bgd.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.24396",
  "fulltext_url": null,
  "id": "98tcb4gwm6bgd",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.24396",
  "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.IM"
    ],
    [
      "openalex",
      "3103|Astrophysical Phenomena and Observations"
    ]
  ],
  "openalex": "W7223026730",
  "pdf_url": "https://arxiv.org/pdf/2610.24396",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-17",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/98tcb4gwm6bgd.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:30:52Z",
      "native_id": "2610.24396",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.24396"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.IM",
      "subfield": "instrumentation-methods"
    }
  ],
  "title": "Prospects for submillimeter VLBI of black hole photon rings with a stratospheric balloon-borne telescope",
  "title_text": "Prospects for submillimeter VLBI of black hole photon rings with a stratospheric balloon-borne telescope",
  "type": "preprint",
  "updated_at": "2026-10-30T12:33:41Z",
  "url": "https://research.draconitic.com/paper/98tcb4gwm6bgd",
  "venue": "arXiv",
  "versions": []
}