Coordinated universal time ―known by its acronym in English UTC ( universal time coordinated) ― or civil time and civil time is the reference time zone with respect to which all other zones of the world are calculated. It is the successor of GMT (Greenwich mean time: Greenwich mean time), and is still colloquially called that. The new name was coined to eliminate the inclusion of a specific location in an international standard, as well as to base the measurement of time on atomic standards, rather than celestial ones.
According to abbreviationfinder, “UTC” isn’t really an abbreviation; is a variant of universal time (universal time, abbreviated UT) and its modifier C (for “coordinated”), added to express that it is one more variant of UT. It can be considered as a compromise between the English abbreviation “CUT” (coordinated universal time) and the French “TUC” (temps universel coordonné).
True high-precision UTC times can only be determined after knowing the fact that atomic time is established by reconciling the observed differences between a set of atomic clocks maintained by a number of national time offices.
However, atomic clocks are so accurate that only the most precise time computers need to use these corrections; and most time service users use atomic clocks that have been previously referenced to UTC, to estimate UTC time.
These clocks cannot present hourly variations greater or less than 0.9 seconds. UTC usually varies a tenth of a second in times of deep winter like July or December where the jump is voluntary and necessary to recalculate and adjust the UT data, since the UT1 data never varies.
Differences between GMT and UTC
Unlike GMT, UTC is not defined by the Sun or the stars, but is instead measured by atomic clocks. Because the earth’s rotation slows down, it lags behind atomic time. UTC is synchronized with the day and night of UT1, with leap seconds added or subtracted in both late June and December, when necessary. The circulation of leap seconds is determined by the International Earth Rotation Service, based on their measurements of the earth’s rotation.
In order to perform the calculations using the UTC method, it is necessary to take into account the zero hour (which happens at exactly midnight), this differentiates it from the GTM (which takes 12 o’clock as the zero hour, since the UTC is established as a 24-hour system, where each hour has its own acronym that is not repeated throughout the day. With this method, the terms before noon (am) and after noon (pm) are no longer used. For example, using GTM it is correct to state that in Colombia it is 5pm, while taking into account the UTC system, it must be stated that in Colombia it is 5pm.
Reasons for changing GMT to UTC
There were two reasons that caused this change from GMT to UTC. The first was precision. With the development of atomic clocks, the standards of time measurements ceased to be celestial to be atomic.
The rotational movement of the Earth, although stable, is not constant, it slows down, which causes a delay in the measurement of the passage of time. Something that does not happen with the one measured by atomic clocks. An atomic clock is a type of clock that uses a normal atomic resonance frequency to power its counter. The first atomic clocks took their reference from a Maser.
Today the best atomic frequency standards are based on the physical properties of the cesium (Cs) emission sources.
Atomic time is established by comparing the observed differences between a set of atomic clocks, guarded and maintained by a number of time offices of different nations.
The second reason for the change was conventional and was actually propitiated by the first. But two details to keep in mind that helped. To begin with, since they were no longer based on the observation of celestial bodies, astronomical observatories lost importance in determining the exact planetary time.
And finally, since it was an international time standard, it was desired to eliminate any reference to geographical location in said denomination. Something less spatial. After all, man lives in time rather than in space.
Zulu or Zulu time, designates in military uses and in aerial navigation the Coordinated Universal Time. Represents the letter Z in the Interco code. Its main merit is that it allows a common time to be used as a reference and not the local times with which a transformation process was required.
Each time zone has a correlative letter as identification, starting with Greenwich. When a time is given in CUT, UTC or Zulu, it is actually the time at 0° longitude which passes through Greenwich, England. All time zones around the world are established in reference to longitude 0 or also known as the Greenwich meridian.