2020A&A...634A..83W

Context. The Galactic plane has been observed extensively by a large number of Galactic plane surveys from infrared to radio wavelengths at an angular resolution below 40''. However, a 21cm line and continuum survey with comparable spatial resolution is lacking. Aims. The first half of THOR data (l=14.0°-37.9°, and l=47.1°-51.2°, |b|≤1.25°) has been published in our data release 1 paper. With this data release 2 paper, we publish all the remaining spectral line data and StokesI continuum data with high angular resolution (10''-40''), including a new HI dataset for the whole THOR survey region (l=14.0-67.4° and |b|≤1.25°). As we published the results of OH lines and continuum emission elsewhere, we concentrate on the HI analysis in this paper. Methods. With the Karl G. Jansky Very Large Array (VLA) in C-configuration, we observed a large portion of the first Galactic quadrant, achieving an angular resolution of ≤40''. At L Band, the WIDAR correlator at the VLA was set to cover the 21cm HI line, four OH transitions, a series of Hnα radio recombination lines (RRLs; n=151 to 186), and eight 128 MHz-wide continuum spectral windows, simultaneously. Results. We publish all OH and RRL data from the C-configuration observations, and a new HI dataset combining VLA C+D+GBT (VLA D-configuration and GBT data are from the VLA Galactic Plane Survey) for the whole survey. The HI emission shows clear filamentary substructures at negative velocities with low velocity crowding. The emission at positive velocities is more smeared-out, likely due to higher spatial and velocity crowding of structures at the positive velocities.