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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.


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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