JST (Japan Standard Time)
jst
JST (Japan Standard Time) is the standard time of Japan at UTC+9, based on the 135th meridian east. Japan does not observe daylight saving time.
NICT (National Institute of Information and Communications Technology)
nict
Overview
NICT (National Institute of Information and Communications Technology) is the Japanese national research and development agency that manages Japan Standard Time. Headquartered in Koganei, Tokyo, it operates 18 cesium atomic clocks along with hydrogen maser clocks to generate and maintain JST.
Time Distribution
NICT distributes Japan Standard Time through several channels: the JJY longwave radio signal (Otakadoya-yama at 40 kHz, Hagane-yama at 60 kHz), NTP servers (ntp.nict.jp) for internet-based synchronization, and time distribution over telephone lines. The Japan Standard Time maintained by NICT also serves as the time source for broadcasters' time signals and for the telephone time service (dial 117) operated by NTT East and NTT West. In addition, NICT contributes atomic clock data to the BIPM for the computation of International Atomic Time (TAI).
Time-Related Research
NICT is a world leader in optical lattice clock research. Its work spans ultra-precise time generation using strontium optical lattice clocks, remote time comparison via optical fiber links, and international time transfer using satellites. The frequency of JST is already calibrated against a strontium optical lattice clock once or twice a week, and making an optical lattice clock the primary standard is under consideration for the future.
Was this article helpful?
Related Terms
Atomic Clock
atomic clock
An atomic clock measures time by using the quantum-mechanical transition frequency of atoms as its reference, achieving accuracies on the order of one second in hundreds of millions of years and forming the backbone of modern timekeeping.
NTP (Network Time Protocol)
ntp
A networking protocol for clock synchronization between computer systems over packet-switched networks.
Related Articles
How Time Zones Work - Understanding UTC Offsets and the Global Time System
Learn how time zones divide the world into regions with different local times, how UTC offsets work, and why some zones use half-hour increments.
The History of Standard Time - How Railways Forced a Global Clock
Before railways, every town kept its own solar time. Trains made that impossible, and within a few decades the world adopted a coordinated system anchored to the Greenwich meridian. This article traces the journey from local solar time through the 1884 International Meridian Conference to UTC.
How Standard Time Is Determined - The International System Behind UTC
UTC is not produced by a single clock but by 80+ research institutions worldwide whose data is averaged by the BIPM in Paris. This article explains TAI, leap second decisions, the distribution channels from satellites to NTP, and the upcoming redefinition of the second.