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Ultra-rapid UT1 measurement by e-VLBI


The latency of UT1 measurement with Very Long Baseline Interferometry (VLBI) has been greatly reduced by using e-VLBI technology. VLBI observations on the baseline formed by the Kashima 34-m and the Onsala 20-m radio telescopes achieved ultra-rapid UT1 measurements, where the UT1 result was obtained within 30 min after the end of the observing session. A high speed network and a UDP-based data transfer protocol ‘Tsunami’ assisted the high data rate and long-distance data transfer from Onsala to Kashima. The accuracy of the UT1 value obtained from the 1-h single baseline e-VLBI experiment has been confirmed to be as the same level with the rapid combined solution of Bulletin-A. The newly developed technology is going to be transferred to the regular intensive VLBI sessions, and it is expected to contribute to the improved latency and accuracy of UT1 data.


  1. Alef, W., E-VLBI Status at the MPIfR, 6th International e-VLBI workshop, evlbi/, 2007.

  2. Behrend, D. and A. Nothnagel, 3.4.3 International VLBI Service (IVS), IERS Annual Report 2006, 46–50, 2007.

  3. Carter, W. E., D. S. Robertson, and J. R. Ray, Earth orientation time series derived from VLBI observations, IERS Tech. Note, 11, 33–39, 1992.

  4. Gipson, J., GSFC VLBI SKED Software Package, sked.htm, 1999.

  5. Haystack Observatory, Mark5/e-VLBI News Letter,, 8, 2006.

  6. Hirabaru, M., Performance Measurement on Large Bandwidth-Delay Product Network, Proceedings of the 3rd International e-VLBI workshop, IVS NICT-TDC News,, 25, 11–19, 2004.

  7. Hobiger, T., Y. Koyama, and T. Kondo, MK3TOOLS & NetCDF—storing VLBI data in a machine independent array oriented data format, Proceeding 18th European VLBI for Geodesy and Astrometry (EVGA) Working Meeting April 12–13, 2007, Vienna, Austria,, P03, 2007.

  8. IERS, Explanatory Supplement to IERS Bulletins A and B,, 2004.

  9. Johnson, T., S. M. Carter, A. Myers, S. Lambert, and W. Wooden, Rapid Service/Prediction Centre, IERS Annual Report 2005, 57–66, 2005.

  10. Kondo, T., Y. Koyama, H. Takeuchi, and M. Kimura, Current Status of the K5 Software Correlator, IVS NICT-TDC News, 25, 23–27, 2004.

  11. Kondo, T., Y. Koyama, H. Takeuchi, and M. Kimura, Development of a New VLBI Sampler Unit (K5/VSSP32) Equipped with a USB 2.0 Interface, in IVS 2006 General Meeting Proceedings, edited by Dirk Behrend and Karen Baver, 195–199, NASA/CP-2006-214140, 2006.

  12. Koyama, Y., T. Kondo, H. Takeuchi, M. Hirabaru, K. Takashima, D. Lapsley, K. Dudevoir, and A. R. Whitney, Rapid turn around UT1 estimation with e-VLBI, IVS NICT-TDC News,, 25, 28–35, 2004.

  13. Ma, C. and D. S. Caprette, Earth orientation parameters, site positions with estimated site velocities, and source positions from the NASA Crustal Dynamics Project Using AM0-2 and two-month stepwise positions from HRAS 085, IERS Tech. Note, 11, 3–16, 1992.

  14. Machida, M., M. Ishimoto, and K. Takashima, Tsukuba VLBI Correlator, in International VLBI Service for Geodesy and Astrometry 2005 Annual Report, edited by D. Behrend and K. Baver, 186–189, NASA/TP-2006-214136, 2006.

  15. McCarthy, D. D. and G. Petit, IERS Conventions (2003), IERS Tech. Note32, 2004.

  16. Meiss, M. R., Tsunami: A High-Speed Rate-Controlled Protocol for File Transfer,, 2004.

  17. Petrov, L., Mark-5 VLBI Analysis Software Calc/Solve,, 2007.

  18. Ritakari, J. and A. Mujunen, Gbit/s VLBI and eVLBI with Off-The-Shelf Components, in International VLBI Service for Geodesy and Astrometry 2004 General Meeting Proceedings, edited by Nancy R. Vandenberg and Karen D. Baver, 182–185, NASA/CP-2004-212255, 2004.

  19. Robertson, D. S., W. E. Carter, J. Campbell, and H. Schuh, Daily earth rotation determinations from IRIS very long baseline interferometry, Nature, 316, 424–427, 1985.

  20. Rogers, A. E. E., Very Long Baseline Interferometry with Large Effective Bandwidth for Phase-Delay Measurements, Radio Sci., 5, 1239–1247, 1970.

  21. Tingay, S., T. Tzioumis, A. Deller, C. Phillips, S. Amy, J. Dickey, S. Ellingsen, B. Reid, S. Gulyaev, and T. Natusch, Summary of current and future e-VLBI developments in Australasia, 6th International e-VLBI workshop, evlbi/, 2007.

  22. Titov, O., V. Tesmer, and J. Boehm, OCCAM v. 6.0 software for VLBI data analysis, in International VLBI Service for Geodesy and Astrometry 2004 General Meeting Proceedings, edited by Nancy R. Vandenberg and Karen D. Baver, 267–271, NASA/CP-2004-212255, 2004.

  23. Whitney, A. R., Future directions in VLBI technology, in EVN Symposium 2000, Proceedings of the 5th European VLBI Network Symposium held at Chalmers University of Technology, Gothenburg, Sweden, June 29–July 1, 2000, edited by J. E. Conway, A. G. Polatidis, R. S. Booth, and Y. M. Pihlstrm, p. 233, 2000.

  24. Whitney, A. R., The Mark 5B VLBI Data System, in International VLBI Service for Geodesy and Astrometry 2004 General Meeting Proceedings, edited by Nancy R. Vandenberg and Karen D. Baver, NASA/CP-2004-212255, 177–181, 2004.

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Correspondence to Mamoru Sekido.

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Sekido, M., Takiguchi, H., Koyama, Y. et al. Ultra-rapid UT1 measurement by e-VLBI. Earth Planet Sp 60, 865–870 (2008).

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Key words

  • E-VLBI
  • UT1