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  2. Greenwich Time Signal - Wikipedia

    en.wikipedia.org/wiki/Greenwich_Time_Signal

    Greenwich Time Signal. Graph of the six pips. The Greenwich Time Signal (GTS), popularly known as the pips, is a series of six short tones (or "pips") broadcast at one-second intervals by many BBC Radio stations to mark the precise start of each hour. The pips were introduced in 1924, generated by the Royal Observatory, Greenwich, and from 1990 ...

  3. Coordinated Universal Time - Wikipedia

    en.wikipedia.org/wiki/Coordinated_Universal_Time

    Coordinated Universal Time (UTC) is the primary time standard globally used to regulate clocks and time. It establishes a reference for the current time, forming the basis for civil time and time zones. UTC facilitates international communication, navigation, scientific research, and commerce. UTC has been widely embraced by most countries and ...

  4. Universal Time - Wikipedia

    en.wikipedia.org/wiki/Universal_Time

    Universal Time (UT or UT1) is a time standard based on Earth's rotation. [1] While originally it was mean solar time at 0° longitude, precise measurements of the Sun are difficult. Therefore, UT1 is computed from a measure of the Earth's angle with respect to the International Celestial Reference Frame (ICRF), called the Earth Rotation Angle ...

  5. Greenwich Mean Time - Wikipedia

    en.wikipedia.org/wiki/Greenwich_Mean_Time

    Greenwich Mean Time is defined in law as standard time in the following countries and areas, which also advance their clocks one hour (GMT+1) in summer. United Kingdom, where the summer time is called British Summer Time (BST) Ireland, where it is called Winter Time, [22] changing to Standard Time in summer. [21]

  6. Marine chronometer - Wikipedia

    en.wikipedia.org/wiki/Marine_chronometer

    It is used to determine longitude by comparing Greenwich Mean Time (GMT), and the time at the current location found from observations of celestial bodies. When first developed in the 18th century, it was a major technical achievement, as accurate knowledge of the time over a long sea voyage was vital for effective navigation , lacking ...

  7. Time zone - Wikipedia

    en.wikipedia.org/wiki/Time_zone

    Time zones of the world. A time zone is an area which observes a uniform standard time for legal, commercial and social purposes. Time zones tend to follow the boundaries between countries and their subdivisions instead of strictly following longitude, because it is convenient for areas in frequent communication to keep the same time.

  8. Unix time - Wikipedia

    en.wikipedia.org/wiki/Unix_time

    Unix time[a] is a date and time representation widely used in computing. It measures time by the number of non- leap seconds that have elapsed since 00:00:00 UTC on 1st January 1970, the Unix epoch. In modern computing, values are sometimes stored with higher granularity, such as microseconds or nanoseconds.

  9. Time signal - Wikipedia

    en.wikipedia.org/wiki/Time_signal

    A time signal is a visible, audible, mechanical, or electronic signal used as a reference to determine the time of day. Church bells or voices announcing hours of prayer gave way to automatically operated chimes on public clocks; however, audible signals (even signal guns) have limited range. Busy seaports used a visual signal, the dropping of ...