## 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 ). In 2017, KaVA system is still being developed and some capabilities are remained to be implemented.

KaVA invites proposals for open use observations to be carried out from 15th January 2018 to 15th June 2018 (2018A). The maximum observing time per proposal is increased to 100 hours from the current call, 2018A. If requested in the proposals, the observation time can be allocated over a year, until 15th January, 2019, for this call. But the maximum observation time will be still limited to 100 hours. This call for proposals (CfP) is offered for open use in a shared-risk mode.

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 multi-frequency 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/eng.

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 (SFR). 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. In 2016, the new papers on maser emission around an asymptotic giant branch (AGB) star WX PSc was published (Yun et al. 2016). These three papers are based on the initial results from KaVA large programs started since 2016, demonstrating high capabilities of KaVA for SFR, AGN, and AGB projects.

KaVA ( KVN and VERA Array )