1. Possible eVLBI connection between Eastern Asian Observatories Noriyuki KAWAGUCHI National Astronomical Observatory, Japan eVLBI Workshop 2008.6.16@Shanghai Observatory

2. Contents (1)Eastern Asian VLBI Network (2)Seoul Correlator (3)Data Transfer to Seoul

3. East Asian VLBI Network 17 radio telescopes 2, 8, 22, 43, 86, 110 GHz 4860km E-W ‘xy-plane’ 1480km ‘z’

4. Real Time Fringe in Japanese eVLBI Observation 2-Gbps Real Time Fringe Data rate of 2-Gbps is an unit of transmission and correlation.

5. Japanese Domestic Connection Real Time eVLBI Connection realized Real Time eVLBI Connection planned Fibers of limited capacity Offline Connection Media Shipping Ogasawara Ishigaki Iriki Yamaguchi Gifu Usuda Nobeyama Ibaraki Kashima Mizusawa Tomakomai Tsukuba

6. Seoul Correlator Capable to correlate 16 stations at the speed of 8 Gbps Supposed observatories are; –VERA 4 stations –KVN 3 stations –Japanese Institutes/Universities 7 stations –Chinese 4 stations Supposed users are –KVN (22, 43, 86, 110 GHz) –VERA+KVN observations (22, 43GHz) –EAVN coordinated observation (8, 22GHz) –VSOP2 ground support (8, 22, 43GHz)

7. Final Integration Test VERA Mark 5 VERA2000 DIO (RVDB) VSI-H 10GbE x 4 VCS Receiver Noise SG tone Coherent Noise Hardware Integration → Hardware/ Software Integration x 2 x 4 KVN Direct Access to Disk via eVLBI connection for the test K5 VERA in future

8. Korean Network (KREONET) KVN Stations –Yonsei University, Seoul –Ulsan –Cheju Island Korean domestic stations (KVN) are to be eVLBI connected in near future.

9. Seoul Taejun Pusan Japanese Stations to Seoul Correlator Koganei, Tokyo 20G 10G 10G to Pusan Japanese Stations Mitaka, Tokyo Taejun- Koganei Is usually 10Gbps but possible to expand to 20Gbps Koganei and Seoul has already been connected through JGN and KREONET. 2G x 4 or 1G x 8 JGN-2+

11. Chinese Stations to Seoul Correlator 10G connection between Hong-Kong and Seoul I am not familiar with chinese communication network.

12. Concluding Remarks (1) Shipping data to Seoul Correlator with eVLBI connection ･ ‘Kreonet’ from Japan to Seoul ・ ‘Groliad’ from China to Seoul (2) Media Shipping with mag. tapes, disks before VSOP2 (3) Hopefully by eVLBI transmission after the VSOP2 launch except Japanese remote island station.