Near Real-time UT1 Measurement by Using e-VLBI Technique Tetsuro Kondo, Yasuhiro Koyama, and Hiroshi Takeuchi, Kashima Space Research Center, National Institute of Information and Communications Technology, 893-1 Hirai, Kashima, Ibaraki 314-0012, Japan (e-mail: kondo@nict.go.jp) Masaki Hirabaru National Institute of Information and Communications Technology, 4-2-1 Nukui-kita, Koganei, Tokyo 184-8795, Japan Kazuhiro Takashima Geographical Survey Institute 1 Kitasato, Tsukuba, Ibraki 305-0811, Japan David Lapsley, Kevin Dudevoir, and Alan Whitney Haystack Observatory, MIT Off Route 40, Westford, MA 01886-1299, USA Recent progress of e-VLBI technique and the increase of network speed made rapid UT1 measurements possible. On June 30, 2004 we performed a one-hour e-VLBI session with the baseline between Kashima and Westford stations to estimate UT1 as rapid as possible. Observation data were recorded with the K5/VSSP system at Kashima and the Mark-5 system at Westford. Immediately after the session was finished, Mark-5 data were transferred to Kashima through the Internet. The Mark-5 data were then converted to K5 format data. In the next step, the converted data were correlated with those recorded at Kashima by using the K5 software correlator combined with the network-distributed processing system named VLBI@home. Finally we succeeded to obtain estimated UT1 value in as short as 4.5 hours after the session was over. To shorten the turn-around time of UT1 estimation further, we are improving the K5 software correlator so as to correlate K5 data with Mark-5 data directly. We are also developing software to send K5 data over network according to the standard data format (VSI-E). In addition to the rapid UT1 measurement results, we will report about current status of these software developments.