Measuring the impact of Indonesian antennas on global geodetic VLBI network

International audienceIn the near future, two radio telescopes will be installed in the Indonesian region. These telescopes are proposed to be integrated into the existing Very Long Baseline Interferometry (VLBI) network both for astronomical and geodetical purposes. Here we simulate the impact of the inclusion of the future Indonesian antennas to the estimates of Earth Orientation Parameters and the station position. The simulation was performed in two types of VLBI sessions. First, we analyse the contribution of Indonesian antennas to the existing intensive session INT3 (IN320-314), which focuses on the estimation of dUT1. We found that the addition of Indonesian antennas has reduced the estimated dUT1 repeatability value by about 25%. Next, we simulate the 24-hour session by considering two existing network configurations, which are R4 (R4934) and AOV (AOV049). Overall we found that the addition of Indonesian antennas to each network configuration decreases the repeatability value of the Earth Orientation Parameter by about 20%. Meanwhile, the repeatability value of station position is reduced up to 12%. This reduction is already achieved even when we include only one Indonesian antenna

Overview of the Observing System and Initial Scientific Accomplishments of the East Asian VLBI Network (EAVN)

The East Asian VLBI Network (EAVN) is an international VLBI facility in East Asia and is operated under mutual collaboration between East Asian countries, as well as part of Southeast Asian and European countries. EAVN currently consists of 16 radio telescopes and three correlators located in China, Japan, and Korea, and is operated mainly at three frequency bands, 6.7, 22, and 43 GHz with the longest baseline length of 5078 km, resulting in the highest angular resolution of 0.28 milliarcseconds at 43 GHz. One of distinct capabilities of EAVN is multi-frequency simultaneous data reception at nine telescopes, which enable us to employ the frequency phase transfer technique to obtain better sensitivity at higher observing frequencies. EAVN started its open-use program in the second half of 2018, providing a total observing time of more than 1100 h in a year. EAVN fills geographical gap in global VLBI array, resulting in enabling us to conduct contiguous high-resolution VLBI observations. EAVN has produced various scientific accomplishments especially in observations toward active galactic nuclei, evolved stars, and star-forming regions. These activities motivate us to initiate launch of the ’Global VLBI Alliance’ to provide an opportunity of VLBI observation with the longest baselines on the earth