GASS: the Parkes Galactic all-sky survey

II. Stray-radiation correction and second data release

¹ Argelander-Institut für Astronomie, Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany e-mail: [pkalberla;jkerp;bwinkel]@astro.uni-bonn.de
² Australia Telescope National Facility, CSIRO, Marsfield NSW 2122, Australia e-mail: [naomi.mcclure-griffiths;mark.calabretta]@csiro.au
³ Department of Physics, West Virginia University, PO Box 6315, Morgantown, WV 26506, USA e-mail: djpisano@mail.wvu.edu
⁴ Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Hawthorn VIC 3122, Australia
⁵ Department of Astronomy, University of Michigan, Ann Arbor, MI 48109, USA e-mail: haford@umich.edu
⁶ National Radio Astronomy Observatory, Green Bank, WV 24944, USA e-mail: jlockman@nrao.edu
⁷ International Centre for Radio Astronomy Research, M468, University of Western Australia, Crawley, WA 6009, Australia e-mail: Lister.Staveley-Smith@icrar.org
⁸ School of Physics, The University of Sydney, NSW 2006, Australia e-mail: tara@physics.usyd.edu.au
⁹ School of Information Technologies, The University of Sydney, NSW 2006, Australia e-mail: katherine.newton-mcgee@defence.gov.au

Received: 28 December 2009
Accepted: 1 July 2010

Abstract

Context. The Parkes Galactic all-sky survey (GASS) is a survey of Galactic atomic hydrogen (H i) emission in the southern sky observed with the Parkes 64-m Radio Telescope. The first data release was published by McClure-Griffiths et al. (2009).

Aims. We remove instrumental effects that affect the GASS and present the second data release.

Methods. We calculate the stray-radiation by convolving the all-sky response of the Parkes antenna with the brightness temperature distribution from the Leiden/Argentine/Bonn (LAB) all sky 21-cm line survey, with major contributions from the 30-m dish of the Instituto Argentino de Radioastronomía (IAR) in the southern sky. Remaining instrumental baselines are corrected using the LAB data for a first guess of emission-free baseline regions. Radio frequency interference is removed by median filtering.

Results. After applying these corrections to the GASS we find an excellent agreement with the Leiden/Argentine/Bonn (LAB) survey. The GASS is the highest spatial resolution, most sensitive, and is currently the most accurate H i survey of the Galactic H i emission in the southern sky. We provide a web interface for generation and download of FITS cubes.