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e-VLBI Deployments with Research Internet. 693276

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very long baseline interferometry (vlbi)

Very Long Baseline Radio Interferometry (VLBI)

VLBI measures the time differences in the arrival of microwave signals from extragalactic radio sources received at two or more radio observatories. Generally, geodetic observing sessions run for 24 hours and observe a number of different radio sources distributed across the sky. The observatories can be widely separated; the sensitivity of the observations to variations in the orientation of the earth increases with the size of the VLBI network.

To date, geocentric coordinates have been measured for about 120 sites, both fixed and "mobile", using the bandwidth synthesis Mark-III (or equivalent) technique. More than half of these have sufficiently long histories that reliable three-dimensional velocity estimates are also available.

Likewise, celestial coordinates have been determined for more than 600 radio sources. These observations are used to maintain the International Celestial Reference Frame (ICRF).

VLBI is the only technique capable of measuring all components of the earth's orientation accurately and simultaneously.

Currently, VLBI determinations of earth-rotation variations, and of the coordinates of terrestrial sites and celestial objects are made routinely and regularly with estimated accuracies of about +/-0.2 milliarcsecond or better.

In the IERS, VLBI is represented by the International VLBI Service (IVS).


https://blackholecam.org/research/bhshadow/vlbi/

Published in: Science
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e-VLBI Deployments with Research Internet. 693276

  1. 1. Hirabaru, Koyama, Kimura, Sekido, Takeuchi, Kondo (NICT) Lapsley, and Whitney (MIT Haystack) Network Engineering and NOC Sessions APAN Conference 2005 in Bangkok January 27, 2005 e-VLBI Deployments with Research Internet
  2. 2. Acknowledgement MAX Gigapop (Jerry Sobieski) TransPAC (Chris Robb) NORDUnet (Lars Fischer) APAN Tokyo NOC (Tanaka, Hattori, Matsui) JGN II NOC (Kakinuma, Hori, Hatachi, Nakamura) NICT R&D NOC (Machizawa, Takemoto, Kitamura) Internet2 (Charles Yun) Metsahovi Radio Observatory (Jouko Ritakari) MIT Haystack (Jason SooHoo, Kevin Dudevoir) Shanghai Observatory (An Tao) JIVE (Sergei Pogrebenko) SURFnet (Erik Radius) Other many networks and institutions…
  3. 3. Radio Telescopes NICT Kashima Space Center 34m Onsala Space Observatory 20m (left) Perks 64m (right) Australia Telescope National Facility MIT Haystack 18m Shanghai 25m
  4. 4. VLBI (Very Long Baseline Interferometry)delay radio signal from a star correlator A/D clock A/D   Internet clock •e-VLBI geographically distributed observation, interconnecting radio antennas over the world Large Bandwidth-Delay Product Network issue ASTRONOMY GEODESY ~Gbps ~Gbps •Gigabit / real-time VLBI multi-gigabit rate sampling A B A B d
  5. 5. Updates since APAN Cairns (July 2004) SC2004 Nov. 8-11, 2004, Pittsburgh JGN II Osaka Jan. 17-18, 2005, Osaka Others (JIVE Dec.22, 2004, Huygens Jan. 14, 2004) e-VLBI Data Transfers and Antennas
  6. 6. e-VLBI SC2004 Network Configuration NICT Kashima MIT Haystack Abilene APAN Tokyo Onsala Stockholm AMS SUNET
  7. 7. e-VLBI Demonstration in SC 2004 (Nov. 2004) MIT Haystack (Westford) GGAO (Maryland) Onsala (SE) NICT Kashima (JP) first 20 minutes every hours 512 Mbps with Haystack and GGAO 256 Mbps with all 4 stations Alan Whitney (Haystack) Charles Yun (I2)Correlation from Haystack Mark 5 Kashima to Haystack via Tokyo XP
  8. 8. MIT Haystack NICT Kashima Abilene (10G) JGN II Int’l (10G) Tokyo JGN II (1G/10G) 1G/2.5G JGN II (10G) Osaka Venue 10G #1 #2 #3 #4 GEN-AGEN-B AA BB AA BB TT SX SX T x4 Raid Raid ファイバー チャンネル LCDLCD NE (Network Emulator) NE T x4 SX x2 SX x2 ファイバー チャンネル TT LCDLCD Measure-B Measure-A e-VLBI Demonstration by NICT JGN II Symposium in Osaka January 17-18, 2005
  9. 9. e-VLBI Demonstration in JGN II Osaka (Jan. 2005) e-VLBI data transfer achieved ~700Mbps from Haystack to Osaka ~900Mbps from Kashima to Osaka Software Cross Correlation ~240Mbps per station Dr. Koyama 4 Apple G5 Server machines (8 CPUs in Total)
  10. 10. Huygens e-VLBI Preliminary Report January 5, 2005 Shanghai to Kashima 1-2 Mbps for 3.8GB x4 January 14, 2005 Shanghai to Kashima 40-50 Mbps No fringe detected Japan - Australia (tsunami) experiment under consideration (Australia Telescope National Facility) "Jouko Ritakari" Jouko.Ritakari@hut.fi reported December 22, 2004 400 Mbit/s eVLBI transfer between NICT Kashima and JIVE using Tsunami protocol. Kashima-JIVE e-VLBI experiment (Dec.22, 2004) Possible Future e-VLBI experiment with Russia NICT Kashima shipped IP VLBI board to Russia (Lebedev Institute) Fibers are available in the nearest town.
  11. 11. e-VLBI Data Transfer Real-time e-VLBI – flat-rate live data transfer Common e-VLBI – file transfer Internet Synchronize Correlation Carry the disk to the nearest station to put on-line Correlate among many combinations concurrently to get more precise data (like a virtual huge antenna) Future - multicast
  12. 12.                                                         VLBI Antenna Locations in North-East Asia Shintotsukawa 3.8m Tomakomai 11m, FTTH (100M) 70km from Sapporo Mizusawa 10m 20m 118km from Sendai Tsukuba 32m, OC48/ATMx2 SuperSINET Kashima 34m, 1Gx2 JGN, OC48/ATM Galaxy Yamaguchi 32m 1G, 75M SINET Gifu 11m 3m, OC48/ATMx2 SuperSINET Usuda 64m, OC48/ATM Galaxy Nobeyama 45m OC48/ATM Galaxy Nanshan (Urumqi) 25m 70km from Urumqi Koganei 34m, 1Gx2 JGN, OC48/ATM Galaxy Miyun (Beijing) 50m 50km from Beijing 2Mbps 2Mbps Yunnan (Kunming) 3m (40m) 10km from Kunming Sheshan (Shanghai) 25m 30km from Shanghai Observatory is on CSTNET at 100M Jeju 20m Tamna U Seoul 20m Yonsei U Ulsan 20m U Ulsan Daejon 14m Taeduk Ishigaki 20m Ogasawara 20m Chichijima 10m Iriki 20m Kagoshima 6m Aira 10m Legend connected not yet connected antenna under construction

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