12CO (3–2) High-Resolution Survey (COHRS) of the Galactic Plane: Complete Data Release

Abstract

We present the full data release of the 12CO (3–2) High-Resolution Survey (COHRS), which has mapped the inner Galactic plane over the range of 9.°5 ≤ l ≤ 62.°3 and ∣b∣ ≤ 0.°5. COHRS has been carried out using the Heterodyne Array Receiver Program on the 15 m James Clerk Maxwell Telescope in Hawaii. The released data are smoothed to have a spatial resolution of 16.″6 and a velocity resolution of 0.635 km s−1, achieving a mean rms of ∼0.6 K on . The COHRS data are useful for investigating detailed three-dimensional structures of individual molecular clouds and large-scale structures such as spiral arms in the Galactic plane. Furthermore, data from other available public surveys of different CO isotopologues and transitions with similar angular resolutions to this survey, such as FUGIN, SEDIGISM, and CHIMPS/CHIMPS2, allow studies of the physical properties of molecular clouds and comparison of their states. In this paper, we report further observations on the second release and improved data reduction since the original COHRS release. We discuss the characteristics of the COHRS data and present integrated-emission images and a position–velocity (PV) map of the region covered. The PV map shows a good match with spiral-arm traces from existing CO and H i surveys. We also obtain and compare integrated one-dimensional distributions of 12CO (1–0) and (3–2) and those of star-forming populations.