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  2. Sidereal time - Wikipedia

    en.wikipedia.org/wiki/Sidereal_time

    Although ERA is intended to replace sidereal time, there is a need to maintain definitions for sidereal time during the transition, and when working with older data and documents. Similarly to mean solar time, every location on Earth has its own local sidereal time (LST), depending on the longitude of the point.

  3. Hour angle - Wikipedia

    en.wikipedia.org/wiki/Hour_angle

    The local hour angle (LHA) of an object in the observer's sky is = or = + where LHA object is the local hour angle of the object, LST is the local sidereal time, is the object's right ascension, GST is Greenwich sidereal time and is the observer's longitude (positive east from the prime meridian). [3]

  4. Time and frequency transfer - Wikipedia

    en.wikipedia.org/wiki/Time_and_frequency_transfer

    In a one-way time transfer system, one end transmits its current time over some communication channel to one or more receivers. [4]: 116 The receivers will, at reception, decode the message, and either just report the time, or adjust a local clock which can provide hold-over time reports in between the reception of messages. The advantage of ...

  5. Universal Time - Wikipedia

    en.wikipedia.org/wiki/Universal_Time

    Standard time zones of the world. The number at the bottom of each zone specifies the number of hours to add to UTC to convert it to the local time. As international commerce increased, the need for an international standard of time measurement emerged. Several authors proposed a "universal" or "cosmic" time (see Time zone § Worldwide time zones).

  6. Time standard - Wikipedia

    en.wikipedia.org/wiki/Time_standard

    A sidereal rotation is the time it takes the Earth to make one revolution with rotation to the stars, approximately 23 hours 56 minutes 4 seconds. A mean solar day is about 3 minutes 56 seconds longer than a mean sidereal day, or 1 ⁄ 366 more than a mean sidereal day. In astronomy, sidereal time is used to predict when a star will reach its ...

  7. Astronomical clock - Wikipedia

    en.wikipedia.org/wiki/Astronomical_clock

    Features include locations of the sun and moon in the zodiac, Julian calendar, Gregorian calendar, sidereal time, GMT, local time with daylight saving time and leap year, solar and lunar cycle corrections, eclipses, local sunset and sunrise, moon phase, tides, sunspot cycles and a planetarium including Pluto's 248-year orbit and the 25 800-year ...

  8. Time-to-digital converter - Wikipedia

    en.wikipedia.org/wiki/Time-to-digital_converter

    The time-to-digital converter measures the time between a start event and a stop event. There is also a digital-to-time converter or delay generator. The delay generator converts a number to a time delay. When the delay generator gets a start pulse at its input, then it outputs a stop pulse after the specified delay.

  9. ΔT (timekeeping) - Wikipedia

    en.wikipedia.org/wiki/ΔT_(timekeeping)

    Universal Time is a time scale based on the Earth's rotation, which is somewhat irregular over short periods (days up to a century), thus any time based on it cannot have an accuracy better than 1 in 10 8. However, a larger, more consistent effect has been observed over many centuries: Earth's rate of rotation is inexorably slowing down. This ...