A panoramic view of the Milky Way HI gas

TL;DR

This paper discusses upcoming high-quality all-sky HI 21-cm line surveys of the Milky Way, which will enable detailed interstellar medium studies and support future high-resolution Galactic imaging.

Contribution

It presents the GASS and EBHIS surveys, detailing their scope, resolution, and how they will combine to create a comprehensive all-sky HI database.

Findings

GASS provides 15 arcmin resolution for the southern sky.

EBHIS offers 9 arcmin resolution for the northern sky.

Combined survey will facilitate high-resolution Galactic studies.

Abstract

Imaging of galaxies to study the interstellar medium on scales of a few pc is difficult. However, for the Milky Way galaxy two major Galactic all sky HI 21-cm line surveys will become available soon with unprecedented quality. We present the Galactic All Sky Survey (GASS) obtained with the Parkes 64-m telescope for the southern hemisphere with a resolution of 15 arcmin. The Effelsberg Bonn HI Survey (EBHIS) will complete the survey for the northern sky with 9 arcmin resolution and we describe this project. A combined All Sky Survey will become available in 2010/2011, early enough to serve as short spacing information for ASKAP. We envision a Galactic 21-cm line database with arcsecond resolution for all declinations <30 deg.