A global view on star formation: The GLOSTAR Galactic plane survey

XII. Effelsberg’s continuum view and data release

¹ Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
² Purple Mountain Observatory, Chinese Academy of Sciences, 10 Yuanhua Road, Nanjing 210023, PR China
³ National Radio Astronomy Observatory, PO Box O, Socorro, NM 87801, USA
⁴ Center for Astrophysics | Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA
⁵ Centre for Astrophysics and Planetary Science, University of Kent, Canterbury CT2 7NH, UK
⁶ National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100101, China
⁷ Key Laboratory of Radio Astronomy and Technology, Chinese Academy of Sciences, A20 Datun Road, Chaoyang District, Beijing 100101, PR China
⁸ Instituto Nacional de Astrofísica, Óptica y Electrónica, Apartado Postal 51 y 216, 72000 Puebla, Mexico
⁹ I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany
¹⁰ Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
¹¹ Department of Earth and Space Science, Indian Institute for Space Science and Technology, Trivandrum 695547, India
¹² Department of Physics, Indian Institute of Science, Bengaluru 560012, India
¹³ Laboratoire d’astrophysique de Bordeaux, Univ. Bordeaux, CNRS, B18N, allée Geoffroy Saint-Hilaire, 33615 Pessac, France

^★ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 6 August 2025
Accepted: 15 December 2025

Abstract

Context. Extended radio continuum emission and its linear polarization play a key role in probing large-scale structures of synchrotron and free-free emission in the Milky Way. Despite the existence of many radio continuum surveys, sensitive, high-angular-resolution single-dish surveys of extended radio continuum emission remain scarce.

Aims. Our objective is to deliver a Galactic plane survey of extended radio continuum emission within the 4–8 GHz frequency range, achieving an unprecedented angular resolution of ≲3^′. As part of the GLObal view of STAR formation (GLOSTAR) survey, we also crucially complement existing data from the Karl G. Jansky Very Large Array (VLA) by addressing the missing zero-spacing gap.

Methods. Within the framework of the GLOSTAR Galactic plane survey, we performed large-scale radio continuum imaging observations toward the Galactic plane in the range −2° < ℓ < 60° and |b| < 1.1°, as well as the Cygnus X region (76° < ℓ < 83° and −1° < b < 2°) with the Effelsberg 100-m Radio Telescope.

Results. We present the Effelsberg continuum survey at 4.89 GHz and 6.82 GHz, including linear polarization, with angular resolutions of 145^′′ and 106^′′, respectively. The survey has been corrected for missing large-scale emission using available low-angular-resolution surveys. Comparison with previous single-dish surveys indicates that our continuum survey represents the highest-quality single-dish data collected to date at this frequency. More than 90% of the flux density missed by the VLA D-array data is effectively recovered by the Effelsberg continuum survey. The improved sensitivity and angular resolution of our survey enable reliable mapping of Galactic magnetic field structures, with polarization data less affected by depolarization than in previous surveys. The GLOSTAR single-dish continuum data will be released publicly, offering a valuable resource for studying extended objects including HII regions, supernova remnants, diffuse interstellar medium, and Galactic structure.