UTC uses the Gregorian calendar. The Network Time Protocol (NTP), designed to synchronise the clocks of computers over the Internet, transmits time information from the UTC system. Coordinated Universal Time (UTC) Current official world time reference for civil and scientific purposes. On the term Coordinated Universal Time, https://en.wikipedia.org/w/index.php?title=Coordinated_Universal_Time&oldid=1015584788, Short description is different from Wikidata, Wikipedia indefinitely move-protected pages, Articles with disputed statements from August 2018, Wikipedia articles scheduled for update tagging, Creative Commons Attribution-ShareAlike License, This page was last edited on 2 April 2021, at 09:14. [8] If only milliseconds precision is needed, clients can obtain the current UTC from a number of official internet UTC servers. The standard before was Greenwich Mean Time (GMT). Standard time is also known as winter time or normal time in some countries. Coordinated Universal Time definition is - the international standard of time that is kept by atomic clocks around the world —abbreviation UTC. "[1], A number of proposals have been made to replace UTC with a new system that would eliminate leap seconds. The westernmost time zone uses UTC−12, being twelve hours behind UTC; the easternmost time zone uses UTC+14, being fourteen hours ahead of UTC. Coordinated Universal Time (UTC) +0000 UTC UTC/GMT is 15:18 on Tuesday, March 30, 2021 Coordinated Universal Time (UTC), UTC +0; The IANA time zone identifier for UTC is UTC. For the time zone that lies between UTC−1 and UTC+1, see, "Zulu time" redirects here. In 1995, the island nation of Kiribati moved those of its atolls in the Line Islands from UTC−10 to UTC+14 so that Kiribati would all be on the same day. Some time signals started to broadcast the DUT1 correction (UT1 − UTC) for applications requiring a closer approximation of UT1 than UTC now provided. In 1956, the U.S. National Bureau of Standards and U.S. Simply mouse over the colored hour-tiles and glance at the hours selected by the column... and done! [4] Leap seconds are inserted as necessary to keep UTC within 0.9 second of the UT1 variant of universal time. [31], In 1958, data was published linking the frequency for the caesium transition, newly established, with the ephemeris second. The reference line or starting point, the Prime Meridian, was determined to be the transit circle at the Royal Observatory in Greenwich, London. Standard time within most time zones is a certain whole number of hours offset from Coordinated Universal Time (UTC), maintained by a large number of … Coordinated Universal Time is a 24-hour time standard that is used to synchronize world clocks. The length of second so defined was practically equal to the second of ephemeris time. UTC is the common time standard across the world. UTC, or Universal Time Coordinated, is the most precise and commonly referred to time … This was tried experimentally in a service known as "Stepped Atomic Time" (SAT), which ticked at the same rate as TAI and used jumps of 0.2 second to stay synchronised with UT2. The origin of these time zones began in the mid 1800's in England. Coordinated Universal Time Conversion Chart Pacific Standard Pacific Daylight PDT CST EST AST Time (PST) UTC Savings Time (PDT) UTC PST MST MDT CDT EDT UTC MIDNIGHT 0000 0800 MIDNIGHT 0000 0700 0000 0100 0200 0300 0400 0800 1:00 A.M. 0100 0900 1:00 A.M. 0100 0800 0100 0200 0300 0400 0500 0900 2:00 A.M. 0200 1000 2:00 A.M. 0200 0900 0200 0300 0400 0500 0600 1000 3:00 A.M. … [1], The system has been adjusted several times, including a brief period during which the time-coordination radio signals broadcast both UTC and "Stepped Atomic Time (SAT)" before a new UTC was adopted in 1970 and implemented in 1972. The ephemeris second is a unit in the system of time that, when used as the independent variable in the laws of motion that govern the movement of the planets and moons in the solar system, enables the laws of motion to accurately predict the observed positions of solar system bodies. Universal Time Coordinated. In April 2001, Rob Seaman of the National Optical Astronomy Observatory proposed that leap seconds be allowed to be added monthly rather than twice yearly. English speakers originally proposed CUT (for "coordinated universal time"), while French speakers proposed TUC (for "temps universel coordonné"). Clocks, calendars, astronomical observations, these are all tools that have been used to establish a time standard in various parts of the world throughout history. Discontinuities in UTC have occurred only at the end of June or December, although there is provision for them to happen at the end of March and September as well as a second preference. Temps Universel Coordonné) – wzorcowy czas ustalany na podstawie TAI (fr. Los Angeles For casual use, UTC is the same as GMT, but is used by the scientific community. There are several versions of Universal Time, which differ by up to a few seconds. [39][40], The first leap second occurred on 30 June 1972. The current version of UTC is defined by International Telecommunication Union Recommendation (ITU-R TF.460-6), Standard-frequency and time-signal emissions,[3] and is based on International Atomic Time (TAI) with leap seconds added at irregular intervals to compensate for the accumulated difference between TAI and time measured by Earth's rotation. Offset: UTC is 0 hours ahead Greenwich Mean Time (GMT) and is used in Universal Coordinated Universal Time (UTC) is the world time standard that regulates clocks and time. It is within about 1 second of mean solar timeat Prime meridian, and is not adjusted for Daylight Saving Time. [26] At the 1884 International Meridian Conference held in Washington, D.C., the local mean solar time at the Royal Observatory, Greenwich in England was chosen to define the Universal day, counted from 0 hours at mean midnight. This time zone converter lets you visually and very quickly convert UTC to GMT and vice-versa. UTC is represented as UTC +0. Within the limits of observable accuracy, ephemeris seconds are of constant length, as are atomic seconds. The coordination of time and frequency transmissions around the world began on 1 January 1960. This publication allowed a value to be chosen for the length of the atomic second that would accord with the celestial laws of motion. These signals ultimately furnish the basis for the setting of all public and private clocks. During Daylight Saving Time the correct time zone is British Summer Time (BST). The International Space Station also uses UTC as a time standard. Time zones are usually defined as differing from UTC by an integer number of hours,[20] although the laws of each jurisdiction would have to be consulted if sub-second accuracy was required. UTC is used in many Internet and World Wide Web standards. [27] In 1928, the term Universal Time (UT) was introduced by the International Astronomical Union to refer to GMT, with the day starting at midnight. Therefore, if it is 8 P.M. UTC, the time in the Pacific Time zone is noon. UTC is commonly referred to as International Time, Universal Time (UT), Zulu Time(U.S. military), or Greenwich Mean Time (GMT). 当前Coordinated Universal Time（UTC） The Time Now是旅程中、拨号时或从事研究的可靠工具。The Time Now提供准确的（美国网络铯钟）同步Coordinated Universal Time（UTC）。 Universal Time Coordinated. Offset: UTC is 0 hours ahead Greenwich Mean Time (GMT) and is used in Universal Coordinated Universal Time (UTC) is the world time standard that regulates clocks and time. (The slope became shallower in the 1980s, 2000s and late 2010s to 2020s because of slight accelerations of Earth's rotation temporarily shortening the day.) Coordinated Universal Time. Universal Time ( UTC ) to Your Local Time and Worldwide Time Conversions, Conversion Time Chart between Universal Time and Local Time In the 25th century, four leap seconds are projected to be required every year, so the current quarterly options would be insufficient. This agreed with civil Greenwich Mean Time (GMT), used on the island of Great Britain since 1847. In a nutshell, Coordinated Universal Time (UTC) is the most widely accepted time standard by which time and clocks are regulated. Other than this, one of the biggest differences between GMT and UTC is that UTC does not observe Daylight Saving Time. On electronic devices which only allow the time zone to be configured using maps or city names, UTC can be selected indirectly by selecting cities such as Accra in Ghana or Reykjavík in Iceland as they are always on UTC and do not currently use Daylight Saving Time. Amateur radio operators often schedule their radio contacts in UTC, because transmissions on some frequencies can be picked up in many time zones. Accuracy of synchronization was ±0.537 seconds. Coordinated Universal Time is a 24-hour time standard that is used to synchronize world clocks. Your clock is 3.0 seconds behind. Over several centuries, the frequency of leap seconds will become problematic. Since then, leap seconds have occurred on average about once every 19 months, always on 30 June or 31 December. This is a list of the UTC time offsets, showing the difference in hours and minutes from Coordinated Universal Time (UTC), from the westernmost (−12:00) to the easternmost (+14:00). The current use of only the leap second opportunities in June and December will be insufficient to maintain a difference of less than 1 second, and it might be decided to introduce leap seconds in March and September. [28] Until the 1950s, broadcast time signals were based on UT, and hence on the rotation of the Earth. GMT was established by international conference in 1884 as … In 1960, the International Radio Consultative Committee formalized the concept of UTC, and it was put into practice the year after. WWV is located near Fort Collins, Colorado, about 100 kilometers north of Denver. The official abbreviation for Coordinated Universal Time is UTC. These discontinuities take the form of leap seconds implemented by a UTC day of irregular length. The Zulu term stems from military usage while Coordinated Universal Time is the civilian term for this 24-hour clock. [32], In 1961, the Bureau International de l'Heure began coordinating the UTC process internationally (but the name Coordinated Universal Time was not formally adopted by the International Astronomical Union until 1967). It is simply described as the 24-hour time standard of the world.Now, you may be wondering how there can be such a universal time for the entire world when there are various time zones and of course the dreaded daylight savings time. Leap seconds are timed to keep DUT1 within the vertical range depicted by this graph. It was soon recognised that having two types of second with different lengths, namely the UTC second and the SI second used in TAI, was a bad idea. Time zones around the world are expressed using positive or negative offsets from UTC, as in the list of time zones by UTC offset. 協定世界時は、歴史的な理由から特定の分野で同義語として扱われるいくつかの用語が存在する。 Coordinated Universal Time or UTC is the primary time standard by which the world regulates clocks and time. Time difference to GMT/UTC. [22] See the list of military time zones for letters used in addition to Z in qualifying time zones other than Greenwich. Weather forecasts and maps all use UTC to avoid confusion about time zones and daylight saving time. [33][34] From then on, there were time steps every few months, and frequency changes at the end of each year. 1:00 AM (1:00) UTC =. [12][13] The leap seconds cannot be predicted far in advance due to the unpredictable rate of the rotation of Earth.[14]. In 1884, the Greenwich Meridian was used for two-thirds of all charts and maps as their Prime Meridian. For casual use, UTC is the same as GMT, but is used by the scientific community. While the rate due to tidal friction alone is about 2.3 ms/cy, the uplift of Canada and Scandinavia by several metres since the last Ice Age has temporarily reduced this to 1.7 ms/cy over the last 2,700 years. [11] Thus, in the UTC time scale, the second and all smaller time units (millisecond, microsecond, etc.) Time periods when the slope reverses direction (slopes upwards, not the vertical segments) are times when the excess LOD is negative, that is, when the LOD is below 86,400 s. As the Earth's rotation continues to slow, positive leap seconds will be required more frequently. This abbreviation comes as a result of the International Telecommunication Union and the International Astronomical Union wanting to use the same abbreviation in all languages. Near the end of the 20th century, with the LOD at 1.3 ms above the nominal value, UTC ran faster than UT by 1.3 ms per day, getting a second ahead roughly every 800 days. What is the purpose of having a time change every year and when did Daylight Saving Time start? Coordinated Universal Time is based on cesium-beam atomic clocks, with leap seconds added to match earth-motion time, where as Greenwich Mean Time is based upon the Earth's rotation and celestial measurements. for flight plans and air traffic control. The idea of Coordinated Universal Time is something called a “time standard.” This term refers to a specific rate at which time passes or specific points in time. Since the NATO phonetic alphabet word for Z is "Zulu", UTC is sometimes known as "Zulu time". [45] The correct reason for leap seconds, then, is not the current difference between actual and nominal LOD, but rather the accumulation of this difference over a period of time: Near the end of the 20th century, this difference was about 1/800 of a second per day; therefore, after about 800 days, it accumulated to 1 second (and a leap second was then added). Each day contains 24 hours and each hour contains 60 minutes. The frequency of leap seconds therefore corresponds to the slope of the diagonal graph segments, and thus to the excess LOD. The expansion of transport and communication during the 19th century created a need for a unified time-keeping system, and time zones were introduced. [25] He referred to the resulting system as Cosmic Time. Offset: UTC is 0 hours ahead Greenwich Mean Time (GMT) and is used in Universal Coordinated Universal Time (UTC) is the world time standard that regulates clocks and time. Earth's rotational speed is very slowly decreasing because of tidal deceleration; this increases the length of the mean solar day. [36], There was also dissatisfaction with the frequent jumps in UTC (and SAT). Until 1972, Greenwich Mean Time (also known as Zulu time) was the same as Universal Time (UT). In other words, it is the base point for all other time zones in the world. UTC (and TAI) would be more and more ahead of UT; it would coincide with local mean time along a meridian drifting slowly eastward (reaching Paris and beyond). The extra second is called a leap second. By extension, it is not possible to compute the precise duration of a time interval that ends in the future and may encompass an unknown number of leap seconds (for example, the number of TAI seconds between "now" and 2099-12-31 23:59:59). NIST radio station WWV broadcasts time and frequency information 24 hours per day, 7 days per week to millions of listeners worldwide. For casual use, UTC is the same as GMT, but is used by the scientific community. [47] The resulting gradual shift of the sun's movements relative to civil time is analogous to the shift of seasons relative to the yearly calendar that results from the calendar year not precisely matching the tropical year length. Privacy & Terms. It is successor to Greenwich Mean Time (GMT). Proposals have been made to abolish time zones and make Coordinated Universal Time the local time worldwide. For example, local time on the east coast of the United States is five hours behind UTC during winter, but four hours behind while daylight saving is observed there.[24]. In 1968, Louis Essen, the inventor of the caesium atomic clock, and G. M. R. Winkler both independently proposed that steps should be of 1 second only. As mentioned above, the phrase, which refers to GMT as counted from midnight, was coined in the 1930s. For sub-microsecond precision, clients can obtain the time from satellite signals. copy protection A software lock placed on a computer program by its developer to thwart piracy. In order to keep Coordinated Universal Time as accurate as possible, two other time standards are used: International Atomic Time or TAI, and Universal Time also known as Solar Time. Time zones use hours and minutes offset from Coordinated Universal Time (UTC), most a whole number of hours, a few are offset by 30 or 45 minutes. Naval Observatory started to develop atomic frequency time scales; by 1959, these time scales were used in generating the WWV time signals, named for the shortwave radio station that broadcasts them. Coordinated Universal Time (abbreviated to UTC) is the primary time standard by which the world regulates clocks and time. The world's timing centers have agreed to keep their time scales closely synchronized - or coordinated - therefore the name Coordinated Universal Time. Two components are used to determine UTC: Universal Time (UT) was created at the International Meridian Conference in 1884. For example, the Pacific Time zone is 8 hours behind UTC. [35] This was the frequency that had been provisionally used in TAI since 1958. The length of the SI second was calibrated on the basis of the second of ephemeris time[32][35] and can now be seen to have a relationship with the mean solar day observed between 1750 and 1892, analysed by Simon Newcomb. [23], UTC does not change with a change of seasons, but local time or civil time may change if a time zone jurisdiction observes daylight saving time (summer time). Coordinated Universal Time (UTC), also referred to as Greenwich Mean Time (GMT), Universal Time (UT), or "Zulu" is an international time scale used in astronomical and aviation publications, weather products, and other documents. UTC was adjusted several times until 1972, when leap seconds were introduced to keep UTC in line with the Earth's rotation, which is not entirely even, and less exact than atomic clocks. For more information about UTC, see Coordinated Universal Time. Mountain Time Zone: 6 hours behind Coordinated Universal Time (UTC-07:00). In 1955, the caesium atomic clock was invented. The long-term rate of change of LOD is approximately +1.7 ms per century. In the graph of DUT1 above, the excess of LOD above the nominal 86,400 s corresponds to the downward slope of the graph between vertical segments. Time difference to GMT/UTC. Läs om UTC på Wikipedia. Near the end of the 20th century, the length of the mean solar day (also known simply as "length of day" or "LOD") was approximately 86,400.0013 s.[43] For this reason, UT is now "slower" than TAI by the difference (or "excess" LOD) of 1.3 ms/day. Other than this, one of the biggest differences between GMT and UTC is that UTC does not observe Daylight Saving Time. This preventative measure was widely used in the mid-1980s but later abandoned by many developers because of … Coordinated Universal Time (UTC) is the world time standard that regulates clocks and time. Coordinated Universal Time is expressed using a 24-hour clock but can be converted into a 12-hour clock (AM and PM). The time zone using UTC is sometimes denoted UTC±00:00 or by the letter Z—a reference to the equivalent nautical time zone (GMT), which has been denoted by a Z since about 1950. It is, within about 1 second, mean solar time at 0° longitude. Uniwersalny czas koordynowany (ang. The unit of UTC is the atomic second, and UTC is widely broadcast by radio signals. As with TAI, UTC is only known with the highest precision in retrospect. Coordinated Universal Time Local time is based on time zone and Coordinated Universal Time (UTC). It is effectively a successor to Greenwich Mean Time (GMT). Time difference from UTC. As mentioned above, the phrase, which refers to GMT as counted from midnight, was coined in the 1930s. UTC is also the time standard used in aviation,[9] e.g. This 24-hour time standard is kept using highly precise atomic clocks combined with the Earth's rotation. Time zone offset. It will take about 50,000 years for a mean solar day to lengthen by one second (at a rate of 2 ms/cy, where cy means century). [29], In 1967, the SI second was redefined in terms of the frequency supplied by a caesium atomic clock. This rate fluctuates within the range of 1.7–2.3 ms/cy. Days are conventionally identified using the Gregorian calendar, but Julian day numbers can also be used. As a result, the SI second is close to 1/86400 of a mean solar day in the mid‑19th century. time standard that the whole world uses to regulate its clocks History of Daylight Savings Time (DST). At the time, Greenwich Mean Time (GMT) was chosen as the world’s time standard. Universal Time (UTC) to Eastern Standard Time (EST) 12 am UTC: is : 8 pm EST: 1 am UTC: is : 9 pm EST: 2 am UTC: is : 10 pm EST: 3 am UTC: is : 11 pm EST: 4 am UTC: is : 12 am EST: 5 am UTC: is : 1 am EST: 6 am UTC: is : 2 am EST: 7 am UTC: is : 3 am EST: 8 am UTC: is : 4 am EST: 9 am UTC: is : 5 am EST: 10 am UTC: is : 6 am EST: 11 am UTC: is : 7 am EST are of variable duration. Universal Time (UT) is a time standard based on Earth's rotation. In order to maintain a close approximation to UT1, UTC occasionally has discontinuities where it changes from one linear function of TAI to another. 5:30 PM (17:30) Previous Day Pacific Daylight. Time zones were identified by successive letters of the alphabet and the Greenwich time zone was marked by a Z as it was the point of origin. UTC stands for Universal Time. Thus it would be necessary to rely on time steps alone to maintain the approximation of UT. UTC to Your Local Time Conversion -- TimeBie. "UTC" redirects here. Since then, GMT is no longer a time standard. [dubious – discuss]. At the same time, the tick rate of UTC was changed to exactly match TAI. It was thought better for time signals to maintain a consistent frequency, and that this frequency should match the SI second. Coordinated Universal Time (or UTC) is the standard time system of the world.It is the standard by which the world regulates clocks and time. UTC is used in plane and ship navigation, where it also sometimes known as Zulu. 14 states have multiple time zones. Who invented it and in what year? The jumps increased in size to 0.1 second. It is not possible to compute the exact time interval elapsed between two UTC timestamps without consulting a table that shows how many leap seconds occurred during that interval. The transit circle is a part of the telescope's mechanics and it is still cited as the prime meridian's original reference (0° longitude). [48] Thus, the time system would lose its fixed connection to the geographic coordinates based on the IERS meridian. Scale: 00:00 00:05 00:10 00:15 00:20 00:25. It is successor to Greenwich Mean Time (GMT). Time zone offset is the time for your geographic region in relation to UTC. 5:00 PM (17:00) Previous Day Pacific Daylight. Thus, leap seconds were inserted at approximately this interval, retarding UTC to keep it synchronised in the long term. It includes countries and regions that observe them during standard time or year-round. GPS time always remains exactly 19 seconds behind TAI (neither system is affected by the leap seconds introduced in UTC). In contrast, astronomical GMT began at mean noon, 12 hours after mean midnight of the same date until 1 January 1925, whereas nautical GMT began at mean noon, 12 hours before mean midnight of the same date, at least until 1805 in the Royal Navy, but persisted much later elsewhere because it was mentioned at the 1884 conference. GMT is known as Greenwich Mean Time. UTC, which stands for Coordinated Universal Time in English and Temps universel coordonné in French, was abbreviated UTC as a compromise between CUT and TUC in English and French, respectively. Today, Greenwich Mean Time (GMT) is only the name of a time zone that is used by a few countries in Africa and Western Europe, including the UK during winter and all year in Iceland. This UTC was intended to permit a very close approximation to UT2. [46], There is a proposal to redefine UTC and abolish leap seconds, so that sundials would very slowly get further out of sync with civil time. For the album by Caspar Brötzmann and Page Hamilton, see, International Earth Rotation and Reference Systems Service, International Bureau of Weights and Measures, "Coordinated Universal Time (UTC) to retain "leap second, National Institute of Standards and Technology 2012, National Institute of Standards and Technology 2011, International Earth Rotation and Reference Systems Service 2011, Military & Civilian Time Designations n.d, "ITU World Radiocommunication Conference set for Geneva, 2–27 November 2015", "Coordinated Universal Time (UTC) to retain 'leap second, "UTC might be redefined without Leap Seconds", "Wait a second... 2015 will be a little longer", "IAU resolutions adopted at the XVIth General Assembly, Grenoble, France, 1976", "Scientists propose 'leap hour' to fix time system", "Standard-frequency and time-signal emissions", "A Few Facts Concerning GMT, UT, and the RGO", "Frequency of caesium in terms of Ephemeris Time", "Time-reckoning for the twentieth century", "Note on Coordinated Universal Time (CCTF/09-32)", National Institute of Standards and Technology, "NIST Time and Frequency Radio Stations: WWV, WWVH, and WWVB", "The leap second: its history and possible future", "Time scales, their users, and leap seconds", "TF.460-4: Standard-frequency and time-signal emissions", Definition of Coordinated Universal Time in German law–ZeitG §1 (3), International Earth Rotation Service; list of differences between TAI and UTC from 1961 to present, W3C Specification about UTC Date and Time, Standard of time definition: UTC, GPS, LORAN and TAI, What is in a name? Therefore, many scientific applications that require precise measurement of long (multi-year) intervals use TAI instead. [42] In earlier centuries, the mean solar day was shorter than 86,400 SI seconds, and in more recent centuries it is longer than 86,400 seconds. Time standards were originally [37] This system was eventually approved, along with the idea of maintaining the UTC second equal to the TAI second. The irregular day lengths mean that fractional Julian days do not work properly with UTC. It accounts for the grand total of the extra length (about 2 milliseconds each) of all the mean solar days since the previous leap second. It's used as the standard time. India's time zone is UTC/GMT (Coordinated Universal Time/Greenwich Mean Time) +5.5 hours. [29][30], In a controversial decision, the frequency of the signals was initially set to match the rate of UT, but then kept at the same frequency by the use of atomic clocks and deliberately allowed to drift away from UT. For casual use, UTC is the same as GMT, but is used by the scientific community. [16][17] The International Earth Rotation and Reference Systems Service (IERS) tracks and publishes the difference between UTC and Universal Time, DUT1 = UT1 − UTC, and introduces discontinuities into UTC to keep DUT1 in the interval (−0.9 s, +0.9 s). [44] The actual rotational period varies on unpredictable factors such as tectonic motion and has to be observed, rather than computed. The offset from world’s standard time (Coordinated Universal Time UTC) expressed as UTC- or UTC+ defines the local time within a time zone. The Greenwich Meridian in London, England. The most commonly used are Coordinated Universal Time (UTC) and UT1 (see § Versions). Such approximations are designated UTC(k), where k is an abbreviation for the time laboratory. Therefore, telemetry from clocks with a known relation to the geoid is used to provide UTC when required, on locations such as those of spacecraft. UTC (Coordinated Universal Time) is one of the well-known names of UTC+0 time zone which is 0h. GMT is 0 hours ahead of UTC. [21] This ensures that all pilots, regardless of location, are using the same 24-hour clock, thus avoiding confusion when flying between time zones. It is effectively a successor to Greenwich Mean Time (GMT). Coordinated Universal Time Please see UTC (Coordinated Universal Time). This is especially true in aviation, where "Zulu" is the universal standard. The National Institute of Standards and Technology - Time and Frequency Division maintains the standard for frequency and time interval for the United States, provides official time to the United States, and carries out a broad program of research and service activities in time and frequency metrology. ... and done 英: “ Universal time Local time worldwide coordinated universal time UTC! The basis for civil and scientific time, coordinated ”, 仏: « universel temps coordonné » など、非公式な表記 同義語... 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