{
  "id": "1712.07163",
  "version": "v1",
  "published": "2017-12-19T19:28:46.000Z",
  "updated": "2017-12-19T19:28:46.000Z",
  "title": "The second Herschel-ATLAS Data Release - III: optical and near-infrared counterparts in the North Galactic Plane field",
  "authors": [
    "Cristina Furlanetto",
    "S. Dye",
    "N. Bourne",
    "S. Maddox",
    "L. Dunne",
    "S. Eales",
    "E. Valiante",
    "M. W. Smith",
    "D. J. B. Smith",
    "R. J. Ivison",
    "E. Ibar"
  ],
  "comment": "19 pages, 24 figures, submitted to MNRAS",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "This paper forms part of the second major public data release of the Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS). In this work, we describe the identification of optical and near-infrared counterparts to the submillimetre detected sources in the $177$ deg$^2$ North Galactic Plane (NGP) field. We used the likelihood ratio method to identify counterparts in the Sloan Digital Sky Survey and in the UKIRT Imaging Deep Sky Survey within a search radius of $10$ arcsec of the H-ATLAS sources with a $4\\sigma$ detection at $250 \\, \\mu$m. We obtained reliable ($R \\ge 0.8 $) optical counterparts with $r< 22.4$ for 42429 H-ATLAS sources ($37.8$ per cent), with an estimated completeness of $71.7$ per cent and a false identification rate of $4.7$ per cent. We also identified counterparts in the near-infrared using deeper $K$-band data which covers a smaller $\\sim25$ deg$^2$. We found reliable near-infrared counterparts to $61.8$ per cent of the $250$-$\\mu$m-selected sources within that area. We assessed the performance of the likelihood ratio method to identify optical and near-infrared counterparts taking into account the depth and area of both input catalogues. Using catalogues with the same surface density of objects in the overlapping $\\sim25$ deg$^2$ area, we obtained that the reliable fraction in the near-infrared ($54.8$ per cent) is significantly higher than in the optical ($36.4$ per cent). Finally, using deep radio data which covers a small region of the NGP field, we found that $80 - 90$ per cent of our reliable identifications are correct.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2017-12-19T19:28:46.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "north galactic plane field",
      "near-infrared counterparts",
      "second herschel-atlas data",
      "terahertz large area survey",
      "imaging deep sky survey"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 19,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}