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Contents

• What's New
• Japan Standard Time (JST)
• What we do
• JJY
• Time Dissemination Service
• FAQs and Data
• Space-Time Standards Laboratory
  

Information

• The URL of Japan Standard Time in large letters has been changed, so please be careful when you use it. The new URL is as follows.
  https://www.nict.go.jp/JST/JST6_E/ (2024年4月22日)
• No leap second will be introduced on January 1, 2026. (2025年7月8日)
  (No leap second was introduced on July 1, 2025.)
• The Time Dissemination by Telephone (TEL-JJY) ended on March 31, 2024. (2024年4月1日)
• As previously announced, we have completed updating the servers used for public NTP services, so all public NTP servers no longer support NTP version 1. Therefore, if you are using NTP version 1, please migrate to NTP version 2 or later. (2024年3月14日)
• "Telephone JJY" will be completely replaced with "Hikari Telephone JJY" on April 1, 2024. (2024年1月4日)
• Japan standard time distribution service over analog telephone lines (Telephone JJY) ends March 31, 2024. (2023年3月15日)

Topics

• Press Release: World's first use of the "Optical lattice clock" to maintain National standard time.
  〜Synchronization with UTC became possible only with the clock of NICT〜(2022年6月10日)
  

LF Standard Time and Frequency Transmission Station

• Periodic maintenance of facilities in the LF Standard Time and Frequency Transmission Stations will be performed. (Links to a Japanese page) (2025年8月8日)
• (Japanese version only)
• Operation Information of LF stations (Japanese version only)

Contents

Welcome to Japan Standard Time (JST) Group. JST Group plays an important role in the Generation, Comparison, and Dissemination of Japan Standard Time and Frequency standard. Please choose the contents you'd like to use.

Contact Us

Please contact us if you have any questions, comments, corrections, or suggestions.

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