J-Net galactic-plane survey of VLBI radio sources for VLBI Exploration of Radio Astrometry (VERA)

In order to search for new VLBI sources in the galactic plane that can be u sed as phase reference sources in differential VLBI, we conducted 22 GHz ob servations of radio sources in the galactic plane using the Japanese VLBI N etwork (J-Net). We have observed 267 VLBI source candidates selected from e xisting radio surveys and have detected 93 sources at a signal-to-noise rat io larger than 5. While 42 of the 93 detected sources had already been dete cted with VLBI at relatively lower frequency (typically 2 to 8 GHz), the re maining 51 are found to be new VLBI sources detected for the first time. Th ese are located within /b/ less than or equal to 5 degrees, and have a larg e number of galactic maser sources around them. Thus, they are potential ca ndidates for phase reference sources for VLBI Exploration of Radio Astromet ry (VERA), which is the first VLBI array dedicated to phase-referencing VLB I astrometry aimed at measuring the parallax and proper motion of maser sou rces in the whole Galaxy.