KVN and VERA Array

Introduction

This document summarizes the current observational capabilities of KaVA (KVN and VERA Array), which is a combined VLBI network of KVN (Korean VLBI Network) and VERA (VLBI Exploration of Radio Astrometry) operated by Korea Astronomy and Space Science Institute (KASI) and National Astronomical Observatory of Japan (NAOJ), respectively (see Figure 1). In 2016, KaVA system is still being developed and some capabilities are remained to be implemented.

KaVA invites proposals for common use observations to be carried out from 15th June 15 2016 to 15th January 2017 (2016B). The maximum observing time per proposal is 48 hours. If requested in the proposals, the observation time can be allocated over a year, until 15th June, 2017, for this call. But the maximum observation time will be NOT increased. Two new observation modes are available from this call, Fast antenna nodding mode and 1-beam hybrid (KVN multi-freuquency support) mode. This call for proposals (CfP) is offered for open use in a shared-risk mode.


array configuration of KaVA

VERA is a Japanese VLBI array to explore the 3-dimensional structure of the Milky Way Galaxy based on high-precision astrometry of Galactic maser sources. VERA array consists of four 20 m radio telescopes located at Mizusawa, Iriki, Ogasawara, and Ishigakijima with baseline ranges from 1000 km to 2300 km. The construction of VERA array was completed in 2002, and it is under regular operation since the fall of 2003. VERA was opened to international users in the K band (22 GHz) and Q band (43 GHz) from 2009. Most unique aspect of VERA is “dual-beam” telescope, which can simultaneously observe nearby two sources. While single-beam VLBI significantly suffers from fluctuation of atmosphere, dual-beam observations with VERA effectively cancel out the atmospheric fluctuations, and then VERA can measure relative positions of target sources to reference sources with higher accuracy based on the ‘phase-referencing’ technique. For more detail, visit the following web site:

http://veraserver.mtk.nao.ac.jp/index.html

KVN is the mm-wavelength VLBI facility in Korea. It consists of three 21 m radio telescopes, which are located in Seoul (Yonsei University), Ulsan (University of Ulsan), and Jeju island (ex-Tamna University), and produces an effective spatial resolution equivalent to that of a 500 km radio telescope. KASI has developed innovative multifrequency band receiver systems, observing four different frequencies at 22, 43, 86, and 129 GHz simultaneously. With this capability, KVN will provide opportunities to study the formation and death processes of stars, the structure and dynamics of our own Galaxy, the nature of Active Galactic Nuclei and so on at milli-arcsecond (mas) resolutions. For more detail, visit the following web site and paper (Lee et al. 2011):

http://kvn.kasi.re.kr/

KaVA was formed in 2010, on the basis of the VLBI collaboration agreement between KASI and NAOJ. KaVA complements baseline length range up to 2270 km, and can achieve a good imaging quality. Currently, KaVA supports observations at K band and Q band in left-hand-circular polarization with a data aggregation rate of 1024 Mega bit per seconds (bps) (=1 Gbps). This document is intended to give astronomers necessary information for proposing observations with KaVA. For more detail, visit the following web site:

http://kava.kasi.re.kr/

In 2014, the first results from KaVA have been published. Matsumoto et al. (2014) report the first VLBI detection of the 44 GHz methanol maser emission associated with a massive star-forming region. They demonstrate the unique capability of KaVA to image extended maser features. Niinuma et al. (2014) report the detailed analysis of KaVA observations of active galactic nuclei (AGN). The paper discuss about imaging quality and flux calibration accuracy of KaVA. These two papers are useful to know basic properties of KaVA.




KASI logo image

KaVA ( KVN and VERA Array )