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.

radio interferometric calibration

self-calibration

system

wide-field

algorithm

techniques: interferometric

w-projection

gain calibration

sky survey

astronomy

Författare

R. J. van Weeren

Harvard-Smithsonian Center for Astrophysics

W. L. Williams

University of Hertfordshire

Universiteit Leiden

Netherlands Institute for Radio Astronomy (ASTRON)

M. J. Hardcastle

University of Hertfordshire

T. W. Shimwell

Universiteit Leiden

D. Rafferty

Universität Hamburg

J. Sabater

University of Edinburgh

G. Heald

Netherlands Institute for Radio Astronomy (ASTRON)

Rijksuniversiteit Groningen

S. S. Sridhar

Netherlands Institute for Radio Astronomy (ASTRON)

Rijksuniversiteit Groningen

T. J. Dijkema

Netherlands Institute for Radio Astronomy (ASTRON)

G. Brunetti

Istituto di Radioastronomia

M. Brüggen

Universität Hamburg

F. Andrade-Santos

Harvard-Smithsonian Center for Astrophysics

G. Ogrean

Harvard-Smithsonian Center for Astrophysics

H. Rottgering

Universiteit Leiden

W. A. Dawson

Lawrence Livermore National Laboratory

W. R. Forman

Harvard-Smithsonian Center for Astrophysics

F. De Gasperin

Universität Hamburg

Universiteit Leiden

C. G. Jones

Harvard-Smithsonian Center for Astrophysics

G. Miley

Universiteit Leiden

L. Rudnick

University of Minnesota System

C. L. Sarazin

University of Virginia

A. Bonafede

Universität Hamburg

P. N. Best

University of Edinburgh

L. Birzan

Universität Hamburg

R. Cassano

Istituto di Radioastronomia

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

Thüringer Landessternwarte Tautenburg

Cathy Horellou

Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik

M. J. Jarvis

University of the Western Cape

University of Oxford

R. P. Kraft

Harvard-Smithsonian Center for Astrophysics

M. Mevius

Netherlands Institute for Radio Astronomy (ASTRON)

H. T. Intema

Universiteit Leiden

National Radio Astronomy Observatory

S. S. Murray

Johns Hopkins University

Harvard-Smithsonian Center for Astrophysics

E. Orru

Netherlands Institute for Radio Astronomy (ASTRON)

R. Pizzo

Netherlands Institute for Radio Astronomy (ASTRON)

A. Simionescu

JAXA Institute of Space and Astronautical Science

A. Stroe

Universiteit Leiden

S. van der Tol

Netherlands Institute for Radio Astronomy (ASTRON)

G. J. White

Open University

Rutherford Appleton Laboratory

Astrophysical Journal, Supplement Series

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

Vol. 223 1 2

Ämneskategorier

Astronomi, astrofysik och kosmologi

DOI

10.3847/0067-0049/223/1/2