{
  "abstract": "Real telescope beams are asymmetric, breaking the simple $B_{\\ell}$ factorisation in harmonic space and coupling modes across $\\ell$ and $m$. We develop a map-domain treatment in which beam convolution is a local, scan-dependent operation applied directly to the time-ordered data (TOD), accommodating the full beam shape and giving a direct handle on intensity-to-polarisation ($I \\rightarrow P$) leakage. A noiseless validation against spherical-harmonic convolution reproduces the input temperature and $B$-mode power spectra up to $\\ell \\simeq 1000$, well beyond the range of primordial $B$-mode science. We outline how the operation maps onto a sparse linear BeamOperator for modular map-making.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.03840",
  "author_total": 1,
  "authors": [
    {
      "name": "Artem Basyrov"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/1t8zmqh5d1ta6.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.03840",
  "fulltext_url": null,
  "id": "1t8zmqh5d1ta6",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.03840",
  "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.CO"
    ],
    [
      "arxiv",
      "astro-ph.IM"
    ],
    [
      "openalex",
      "3103|Cosmology and Gravitation Theories"
    ]
  ],
  "openalex": "W7220664354",
  "pdf_url": "https://arxiv.org/pdf/2610.03840",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-02",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/1t8zmqh5d1ta6.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:27:01Z",
      "native_id": "2610.03840",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.03840"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.CO",
      "subfield": "cosmology"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.IM",
      "subfield": "instrumentation-methods"
    }
  ],
  "title": "Map-based asymmetric beam treatment: application of real-space beam patterns in CMB data analysis",
  "title_text": "Map-based asymmetric beam treatment: application of real-space beam patterns in CMB data analysis",
  "type": "preprint",
  "updated_at": "2026-10-30T12:27:01Z",
  "url": "https://research.draconitic.com/paper/1t8zmqh5d1ta6",
  "venue": "arXiv",
  "versions": []
}