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  2. Longitude - Wikipedia

    en.wikipedia.org/wiki/Longitude

    Scientifically precise local time varies with longitude: a difference of 15° longitude corresponds to a one-hour difference in local time, due to the differing position in relation to the Sun. Comparing local time to an absolute measure of time allows longitude to be determined. Depending on the era, the absolute time might be obtained from a ...

  3. Longitude by chronometer - Wikipedia

    en.wikipedia.org/wiki/Longitude_by_chronometer

    To determine "longitude by chronometer," a navigator requires a chronometer set to the local time at the Prime Meridian. Local time at the Prime Meridian has historically been called Greenwich Mean Time (GMT), but now, due to international sensitivities, has been renamed as Coordinated Universal Time (UTC), and is known colloquially as "zulu time".

  4. Coordinate time - Wikipedia

    en.wikipedia.org/wiki/Coordinate_time

    However, from the standpoint of Earth-based observers, general time dilation including gravitational time dilation causes Barycentric Coordinate Time, which is based on the SI second, to appear when observed from the Earth to have time units that pass more quickly than SI seconds measured by an Earth-based clock, with a rate of divergence of ...

  5. Local mean time - Wikipedia

    en.wikipedia.org/wiki/Local_mean_time

    Local mean time (LMT) is a form of solar time that corrects the variations of local apparent time, forming a uniform time scale at a specific longitude. This measurement of time was used for everyday use during the 19th century before time zones were introduced beginning in the late 19th century; it still has some uses in astronomy and ...

  6. 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 ...

  7. Sunrise equation - Wikipedia

    en.wikipedia.org/wiki/Sunrise_equation

    The sunrise equation or sunset equation can be used to derive the time of ... latitude = 33.00801 longitude = 35.08794 elevation = 0 print (calc (time (), latitude ...

  8. Marine chronometer - Wikipedia

    en.wikipedia.org/wiki/Marine_chronometer

    A marine chronometer is a precision timepiece that is carried on a ship and employed in the determination of the ship's position by celestial navigation.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.

  9. Equation of time - Wikipedia

    en.wikipedia.org/wiki/Equation_of_time

    The equation of time is the east or west component of the analemma, a curve representing the angular offset of the Sun from its mean position on the celestial sphere as viewed from Earth. The equation of time values for each day of the year, compiled by astronomical observatories, were widely listed in almanacs and ephemerides. [2] [3]: 14