{
  "abstract": "The Canadian Galactic Emission Mapper (CGEM) radio telescope is mapping polarized Galactic foregrounds from 8-10 GHz to aid in the search for B-modes in the Cosmic Microwave Background (CMB). Here we describe the design and early on-sky characterization of the CGEM optics. CGEM employs an on-axis, hat feed optical design that is a body of revolution (BOR) and exhibits excellent intrinsic polarization purity. We describe how we have optimized the optics with a novel framework that can directly minimize simulated intensity to polarized intensity ($T\\rightarrow P$) leakage in angular power spectrum space. The optimized optics exhibit simulated $T\\rightarrow P$ leakage that is orders of magnitude below anticipated $C_\\ell^{BB}$ for $r = 10^{-3}$ when scaled from 8-10 GHz to the CMB observing window near 95 GHz. We go on to describe the mechanical design of the optics, including a novel secondary mirror support made from Astroquartz composite that has low loss, low dielectric constant, and preserves the BOR symmetry of the optics. We then showcase the early on-sky performance of the optics with observations of the Sun and satellites, which probe the beam to 40 dB down from the peak. A beam model for the deployed CGEM optics based on electromagnetic simulations is in excellent agreement with the on-sky data.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2608.28159",
  "author_total": 15,
  "authors": [
    {
      "name": "Joshua MacEachern"
    },
    {
      "name": "Mandana Amiri"
    },
    {
      "name": "Charles L. Bennett"
    },
    {
      "name": "Guinevere Berg"
    },
    {
      "name": "Mark Halpern"
    },
    {
      "name": "Gary Hinshaw"
    },
    {
      "name": "Gordon Lacy"
    },
    {
      "name": "Thomas J. Rennie"
    },
    {
      "name": "Shuyu van Kerkwijk"
    },
    {
      "name": "Bruce Veidt"
    },
    {
      "name": "Pedro Villalba-González"
    },
    {
      "name": "Janet Weiland"
    },
    {
      "name": "Don Wiebe"
    },
    {
      "name": "Edward J. Wollack"
    },
    {
      "name": "Parham Zarei"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/dsxgvz7pwtza9.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2608.28159",
  "fulltext_url": null,
  "id": "dsxgvz7pwtza9",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2608.28159",
  "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.CO"
    ],
    [
      "arxiv",
      "astro-ph.IM"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2608.28159",
  "pmcid": null,
  "pmid": null,
  "published": "2026-08-28",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/dsxgvz7pwtza9.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:22Z",
      "native_id": "2608.28159",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2608.28159"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.CO",
      "subfield": "cosmology"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.IM",
      "subfield": "instrumentation-methods"
    }
  ],
  "title": "The Canadian Galactic Emission Mapper: A New 8-10 GHz Telescope to Map the Polarization of the Northern Sky",
  "title_text": "The Canadian Galactic Emission Mapper: A New 8-10 GHz Telescope to Map the Polarization of the Northern Sky",
  "type": "preprint",
  "updated_at": "2026-10-30T12:17:22Z",
  "url": "https://research.draconitic.com/paper/dsxgvz7pwtza9",
  "venue": "arXiv",
  "versions": [
    {
      "doi": "10.1117/12.3104077",
      "pid": null,
      "relation": "published-as",
      "title": null,
      "venue": null
    }
  ]
}