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Capabilities and prospects of the East Asia Very Long Baseline Interferometry Network

Abstract

The very long baseline interferometry (VLBI) technique offers angular resolutions superior to any other instruments at other wavelengths, enabling unique science applications of high-resolution imaging of radio sources and high-precision astrometry. The East Asia VLBI Network (EAVN) is a collaborative effort in the East Asian region. The EAVN currently consists of 21 telescopes with diverse equipment configurations and frequency setups, allowing flexible subarrays for specific science projects. The EAVN provides the highest resolution of 0.5 mas at 22 GHz, allowing the fine imaging of jets in active galactic nuclei, high-accuracy astrometry of masers and pulsars, and precise spacecraft positioning. The soon-to-be-operational Five-hundred-meter Aperture Spherical radio Telescope (FAST) will open a new era for the EAVN. This state-of-the-art VLBI array also provides easy access to and crucial training for the burgeoning Asian astronomical community. This Perspective summarizes the status, capabilities and prospects of the EAVN.

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Fig. 1: Geographic distribution of the EAVN telescopes and correlators.
Fig. 2: Comparison of uv coverages on a 12-hour track of the EAVN with the EVN and the VLBA at 22 GHz frequency band.
Fig. 3: A sketch map of the EAVN science cases and corresponding subarrays and frequency setups.
Fig. 4: The radio structure of the giant radio galaxy M87.
Fig. 5: Interstellar masers (harboured in star-forming regions) are used for determining the Galactic structure.
Fig. 6: Motion of the Chang'E-3 rover with respect to the lander determined by phase-referencing VLBI, which produces an image at each parking site from A to E.

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Acknowledgements

T.A. thanks the grant supported by the Ministry of Science and Technology of China (2016YFE0100300), the Youth Innovation Promotion Association and FAST Fellowship of Chinese Academy of Sciences. H.I. thanks the grants supported by KAKENHI (16H02167) and the Korea Astronomy and Space Science Institute Commissioning Program. The authors are grateful to the engineering and scientific teams of the EAVN for test experiments. The authors thank Y. Hagiwara for his contribution in preparing the draft, W. Baan, D. Byun, R. Dodson, S. Frey, K. Fujisawa, K. Hada, M. Honma, D.R. Jiang, T. Jung, M. Kino, S.-S. Lee, D. Li, P. Mohan, R.D. Nan, C.S. Oh, Z.H. Qian, M. Rioja, K. Shibata, F.W. Tong, K. Wajima, N. Wang, S.H. Ye, Y. Yonekura and Y.J. Yun for comments on the manuscript and for providing helpful information. B.W.S. is grateful for the support of the National Research Council of Science and Technology, Korea (EU-16-001).

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T.A. coordinated the writing of the paper. All authors have contributed to the EAVN commissioning and the preparation for this Perspective.

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An, T., Sohn, B.W. & Imai, H. Capabilities and prospects of the East Asia Very Long Baseline Interferometry Network. Nat Astron 2, 118–125 (2018). https://doi.org/10.1038/s41550-017-0277-z

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