TERRAPUB Earth, Planets and Space

Earth Planets Space, Vol. 60 (No. 8), pp. 865-870, 2008


Ultra-rapid UT1 measurement by e-VLBI

Mamoru Sekido1, Hiroshi Takiguchi1, Yasuhiro Koyama1, Tetsuro Kondo1, Rüdiger Haas2, Jan Wagner3, Jouko Ritakari3, Shinobu Kurihara4, and Kensuke Kokado4

1National Institute of Information and Communications technology, Kashima Space Research Center, 893-1, Hirai, Kashima, Ibaraki 314-8501, Japan
2Chalmers University of Technology, Onsala Space Observatory, SE-439 92 Onsala, Sweden
3Helsinki University of Technology, Metsähovi Radio Observatory, Metsähovintie 114 FIN-02540 Kylmälä, Finland
4Geographical Survey Institute, 1 Kitasato, Tsukuba 305-0811, Japan

(Received October 31, 2007; Revised May 13, 2008; Accepted June 6, 2008; Online published September 8, 2008)

Abstract: 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.
Key words: E-VLBI, UT1.

Corresponding author E-mail: sekido@nict.go.jp

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