VERA Project

In this paper we review the current status of VERA (VLBI Exploration of Radio Astrometry) project. First, we present an overview of VERA, and then we report on recent results from VERA, particularly the parallax measurement of Galactic star forming region S269 at the distance of 5.3 kpc.

VERA (VLBI Exploration of Radio Astrometry) is Japanese VLBI array dedicated to VLBI astrometry (Honma et al. 2000; Kobayashi et al. 2003 and references therein). The main objective of VERA is to study the 3-D structure and dynamics of the Galaxy through the high-precision astrometry of Galactic maser sources. In order to achieve astrometric accuracy that is required for Galaxy-scale astrometry (~ 10μas), VERA utilize the phase-referencing VLBI technic. As an optimized system for phase-referencing, VERA is the only existing VLBI array that is installed with dual-beam system, which allows us to observe simultaneously a target and a reference to effectively cancel out the tropospheric fluctuations. Thus, VERA can be regarded as an ultimate array for phase-referencing VLBI astrometry. In the present paper, we introduce the VERA project and report on the recent results of astrometric measurements.