A New Catalog of Radio Compact H ii Regions in the Milky Way. II. The 1.4 GHz Data

Abstract

We use a new Very Large Array Galactic plane catalog at 1.4 GHz covering the first and second Galactic quadrants (340 deg deg,|b| deg deg and |b| deg deg) in conjunction with the MSX6C Galactic plane mid-IR catalog to supplement and better understand our 5 GHz catalog. A radio catalog of this region was first published by Zoonematkermani et al., but we have rereduced the data with significantly improved calibration and mosaicking procedures, resulting in more than a tripling of the number of 1.4 GHz sources detected. Comparison of the new 1.4 GHz catalog and the MSX6C catalog resulted in a sample of 556 matches, out of which we estimate only 11 to be chance coincidences. Most of the matches show red Midcourse Space Experiment colors. The scale height of their Galactic latitude distribution is 24'-28' (FWHM) or ~60-70 pc (for a distance of 8.5 kpc), depending on longitude. The latitude distribution flattens out significantly above l~40 deg, and the number of matches drops off sharply.