{
  "abstract": "We report the discovery and spectroscopic confirmation of SN Helios, a strongly lensed, multiply imaged Type II supernova (SN) at $z=3.34$ behind the galaxy cluster RXC J0018.5+1626. The transient was identified as a red F150W-dropout source (F277W = 26.1 mag) in JWST/NIRCam imaging taken on 2026 July 3 for the VENUS survey, with no counterpart in 2024 December imaging. Director's Discretionary Time observations on 2026 August 17 added second-epoch NIRCam imaging and a deep NIRSpec prism spectrum. The spectrum shows a strong, spectrally resolved H$α$ emission line (FWHM $\\approx 7900$ km/s) with a P-Cygni absorption blueshifted by 8800 km/s, together with corresponding H$β$ and He I $λ$10830 features, establishing a hydrogen-rich photosphere at $z=3.34$. Template fits classify SN Helios as a Type II SN, and light-curve comparisons with well-studied local SNe II yield a phase of $27.5\\pm2.8$ rest-frame days past B-band maximum. Independent cluster lens models magnify the observed image by $μ\\approx 10$-20 and predict another image within $\\simeq 2$-6 yr, offering a rare opportunity for a time-delay measurement of $H_{0}$ with a source at $z>3$. The host galaxy is undetected in deep rest-frame ultraviolet and optical imaging, in emission lines, and in ALMA 2 mm dust continuum, leaving a heavily obscured counterpart unlikely. Its de-lensed $M_{\\rm UV}\\gtrsim -13$ places it far below blank-field limits and adds support to an elevated core-collapse rate per unit star formation in ultra-faint galaxies. Without the multi-epoch data, SN Helios would masquerade as a convincing $z\\approx 16$ Lyman-break galaxy, with galaxy-template fits strongly disfavoring any low-redshift solution even with multiple medium bands. Its spectrum thus provides an empirical SED template with which high-redshift searches can vet similar dropout candidates.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.30440",
  "author_total": 66,
  "authors": [
    {
      "name": "Seiji Fujimoto"
    },
    {
      "name": "Conor Larison"
    },
    {
      "name": "Justin D. R. Pierel"
    },
    {
      "name": "Lukas J. Furtak"
    },
    {
      "name": "Masamune Oguri"
    },
    {
      "name": "Adi Zitrin"
    },
    {
      "name": "Jose M. Diego"
    },
    {
      "name": "Keren Sharon"
    },
    {
      "name": "David A. Coulter"
    },
    {
      "name": "Gabriel Brammer"
    },
    {
      "name": "Vasily Kokorev"
    },
    {
      "name": "Chelsea Nash"
    },
    {
      "name": "Pedram Abedi"
    },
    {
      "name": "Christa DeCoursey"
    },
    {
      "name": "Armin Rest"
    },
    {
      "name": "Andreas L. Faisst"
    },
    {
      "name": "Brenda L. Frye"
    },
    {
      "name": "Tiger Yu-Yang Hsiao"
    },
    {
      "name": "Kohei Inayoshi"
    },
    {
      "name": "Kotaro Kohno"
    },
    {
      "name": "Jorryt Matthee"
    },
    {
      "name": "Matteo Messa"
    },
    {
      "name": "Yoshiaki Ono"
    },
    {
      "name": "Fengwu Sun"
    },
    {
      "name": "Eros Vanzella"
    },
    {
      "name": "Rogier A. Windhorst"
    },
    {
      "name": "Abdurro'uf"
    },
    {
      "name": "Aadya Agrawal"
    },
    {
      "name": "Joseph F. V. Allingham"
    },
    {
      "name": "Yoshihisa Asada"
    },
    {
      "name": "Hakim Atek"
    },
    {
      "name": "Maruša Bradač"
    },
    {
      "name": "Larry D. Bradley"
    },
    {
      "name": "Mateusz Bronikowski"
    },
    {
      "name": "Dan Coe"
    },
    {
      "name": "Christopher J. Conselice"
    },
    {
      "name": "Pratika Dayal"
    },
    {
      "name": "Eiichi Egami"
    },
    {
      "name": "Michael Engesser"
    },
    {
      "name": "Gavin Scott Farley"
    },
    {
      "name": "Qinyue Fei"
    },
    {
      "name": "Ori D. Fox"
    },
    {
      "name": "Yoshinobu Fudamoto"
    },
    {
      "name": "Miriam Golubchik"
    },
    {
      "name": "Yuichi Harikane"
    },
    {
      "name": "Gourav Khullar"
    },
    {
      "name": "Tomokazu Kiyota"
    },
    {
      "name": "Paulo A. A. Lopes"
    },
    {
      "name": "Ray A. Lucas"
    },
    {
      "name": "Guillaume Mahler"
    },
    {
      "name": "Ashish Kumar Meena"
    },
    {
      "name": "Rohan P. Naidu"
    },
    {
      "name": "Gautham Narayan"
    },
    {
      "name": "Gaël Noirot"
    },
    {
      "name": "Pascal A. Oesch"
    },
    {
      "name": "Masami Ouchi"
    },
    {
      "name": "José María Palencia"
    },
    {
      "name": "Massimo Pascale"
    },
    {
      "name": "Luke Robbins"
    },
    {
      "name": "M. R. Siebert"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/7whkppn3dkxw0.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.30440",
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  "id": "7whkppn3dkxw0",
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  "landing_url": "https://arxiv.org/abs/2609.30440",
  "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",
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      "astro-ph.CO"
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      "arxiv",
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    [
      "arxiv",
      "astro-ph.HE"
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      "openalex",
      "3103|Gamma-ray bursts and supernovae"
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  "pdf_url": "https://arxiv.org/pdf/2609.30440",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-21",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/7whkppn3dkxw0.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:34:18Z",
      "native_id": "2609.30440",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.30440"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.CO",
      "subfield": "cosmology"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.HE",
      "subfield": "high-energy-astrophysics"
    }
  ],
  "title": "SN Helios: A Multiply Imaged Type II Supernova Opening Time-Delay Cosmography beyond redshift of 3",
  "title_text": "SN Helios: A Multiply Imaged Type II Supernova Opening Time-Delay Cosmography beyond redshift of 3",
  "type": "preprint",
  "updated_at": "2026-10-30T12:34:18Z",
  "url": "https://research.draconitic.com/paper/7whkppn3dkxw0",
  "venue": "arXiv",
  "versions": []
}