A global view on star formation: The GLOSTAR Galactic plane survey. XI. Radio source catalog IV: 2∘<ℓ<28∘, 36∘<ℓ<60∘ and |b|<1∘

Context. The GLOSTAR survey studies star formation with the Very Large Array (VLA) and the Effelsberg 100 meter radio telescope in the Galactic plane between −2 ◦ < ℓ < 60◦ and |b| < 1 ◦ , and the Cygnus X region (76◦ < ℓ < 83◦ and −1 ◦ < b < 2 ◦ ) with unprecedented sensitivity in both flux density (1σ ∼50 µJy beam−1 ) and the capability of detecting emission with angular scales in the range from 1.′′0 to the largest radio structures in the Galaxy on the order of a few degrees size.

Aims. Here, we provide a complete GLOSTAR-VLA D-configuration radio source catalog for the covered part of the Galactic disk. A catalog for the “pilot region” between 28◦ < ℓ < 36◦ has been published in a previous paper and here we present the complementary catalog for the area within 2◦ < ℓ < 28◦ , 36◦ < ℓ < 60◦

and |b| < 1 ◦ .

Methods. Observations were taken with the VLA in a 4 – 8 GHz band to image 100 square degrees of the inner Galactic disk at a reference frequency of 5.8 GHz, using a total of 260 hours of telescope time. We determined spectral indices (α; S ν ∝ ν α ) inside the observed band and in the frequency range 1.4 – 5.8 GHz by complementing our results with those from the THOR survey, which covers 1 – 2 GHz.

Results. The final images have an angular resolution of 18′′ and an average sensitivity of 123 µJy beam−1 . The sensitivity is better (∼ 60 µJy beam−1) in areas free of extended emission. The complementary Galactic disk catalog, presented in this work, consists of 11 211 radio sources. Of these, 1 965 are known large-scale structure sources such as star-forming region complexes, well-known supernova remnants (SNRs), SNR candidates or parts thereof. The remaining 9 227 are discrete individual sources. Source parameters, namely flux densities, sizes, spectral indices, and classifications are reported. We identify 769 H ii region candidates, 359 of which are newly classified as such. The mean value of spectral indices of 225 H ii regions is +0.14 ± 0.02, consistent with most of them emitting optically thin thermal radio emission. Combining our results with the previously published catalog of the pilot region, the final GLOSTAR-VLA D-configuration catalog contains 12 981 radio sources.