LOFAR Facet Calibration
Artikel i vetenskaplig tidskrift, 2016

LOFAR, the Low-Frequency Array, is a powerful new radio telescope operating between 10 and 240 MHz. LOFAR allows detailed sensitive high-resolution studies of the low-frequency radio sky. At the same time LOFAR also provides excellent short baseline coverage to map diffuse extended emission. However, producing highquality deep images is challenging due to the presence of direction-dependent calibration errors, caused by imperfect knowledge of the station beam shapes and the ionosphere. Furthermore, the large data volume and presence of station clock errors present additional difficulties. In this paper we present a new calibration scheme, which we name facet calibration, to obtain deep high-resolution LOFAR High Band Antenna images using the Dutch part of the array. This scheme solves and corrects the direction-dependent errors in a number of facets that cover the observed field of view. Facet calibration provides close to thermal noise limited images for a typical 8 hr observing run at similar to 5. resolution, meeting the specifications of the LOFAR Tier-1 northern survey.

gain calibration

astronomy

radio interferometric calibration

techniques: interferometric

w-projection

system

wide-field

sky survey

algorithm

self-calibration

Författare

R. J. van Weeren

Harvard-Smithsonian Center for Astrophysics

W. L. Williams

University of Hertfordshire

Netherlands Foundation for Research in Astronomy

Leiden Observatory Research Institute

M. J. Hardcastle

University of Hertfordshire

T. W. Shimwell

Leiden Observatory Research Institute

D. Rafferty

Universitat Hamburg

J. Sabater

University of Edinburgh

G. Heald

Netherlands Foundation for Research in Astronomy

University of Groningen, Kapteyn Astronomical Institute

S. S. Sridhar

University of Groningen, Kapteyn Astronomical Institute

Netherlands Foundation for Research in Astronomy

T. J. Dijkema

Netherlands Foundation for Research in Astronomy

G. Brunetti

Istituto Di Radioastronomia, Bologna

M. Brüggen

Universitat Hamburg

F. Andrade-Santos

Harvard-Smithsonian Center for Astrophysics

G. Ogrean

Harvard-Smithsonian Center for Astrophysics

H. Rottgering

Leiden Observatory Research Institute

W. A. Dawson

Lawrence Livermore National Laboratory

W. R. Forman

Harvard-Smithsonian Center for Astrophysics

F. De Gasperin

Leiden Observatory Research Institute

Universitat Hamburg

C. G. Jones

Harvard-Smithsonian Center for Astrophysics

G. Miley

Leiden Observatory Research Institute

L. Rudnick

University of Minnesota System

C. L. Sarazin

University of Virginia

A. Bonafede

Universitat Hamburg

P. N. Best

University of Edinburgh

L. Birzan

Universitat Hamburg

R. Cassano

Istituto Di Radioastronomia, Bologna

K.T. Chyz̊y

Uniwersytet Jagiellonski w Krakowie

J. H. Croston

University of Southampton

T.A. Enßlin

Max Planck-institutet

C. Ferrari

Observatoire de la Cote d'Azur

M. Hoeft

Thuringer Landessternwarte Tautenburg

Cathy Horellou

Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik

M. J. Jarvis

University of Oxford

University of the Western Cape

R. P. Kraft

Harvard-Smithsonian Center for Astrophysics

M. Mevius

Netherlands Foundation for Research in Astronomy

H. T. Intema

National Radio Astronomy Observatory

Leiden Observatory Research Institute

S. S. Murray

Johns Hopkins University

Harvard-Smithsonian Center for Astrophysics

E. Orru

Netherlands Foundation for Research in Astronomy

R. Pizzo

Netherlands Foundation for Research in Astronomy

A. Simionescu

JAXA Institute of Space and Astronautical Science

A. Stroe

Leiden Observatory Research Institute

S. van der Tol

Netherlands Foundation for Research in Astronomy

G. J. White

Open University

Rutherford Appleton Laboratory

Astrophysical Journal, Supplement Series

0067-0049 (ISSN) 1538-4365 (eISSN)

Vol. 223 2

Ämneskategorier

Astronomi, astrofysik och kosmologi

DOI

10.3847/0067-0049/223/1/2