What is G M T ever we see this word in time related?

Question

i know that I S T is indian standard time

Answer 1

GMT is grenwich mean time and is the base or prme meridian from which longitudes are calcluated.  GMT is on 0 degree longitude.  India lies between 70 - 90 degrees longitude and india has picked 82.5 degree as the central longitude for its time and this is IST 5.5 hours ahead (82.5 / 15) of GMT

AM

Answer 2

its the proper time in england and a center line of earth that runs through greenwich in london.

Answer 3

Greenwich Mean Time.

In the UK We have GMT in the Autumn & Winter months and BST (British Summer Time) in the Spring and Summer months when the clocks advance by 1 hour.  

Answer 4

GMT stands for Greenwich Mean Time and is set and monitored at the Greenwich Observatory in London. It's the standard, arbitrary line which the world uses to set it's own time zones by. Between March and October the British time zone changes to British Summer Time which is one hour ahead and is known as Daylight Saving Time in other parts of the world. Hope this helps.

Answer 5

As you have already been told, GMT stands for Greenwich Mean Time, the worldwide accepted arbitrary prime meridian passing through the Royal Observatory of Greenwich, outside London, UK.

Latitudes have always been easy to find: The elevation of the North Star gives parallel lines named after that said elevation. But the longitudes were not accurate before John Harrison invented the marine chronometer at the end of the 18th century.

Longitudes are simply hour angles measured from an arbitrary reference place. During the centuries it has been Greenwich but also Paris, Amsterdam, Rome and even the Canary islands at the time of Christopher Columbus.

The French have long resisted the use of Greenwich, a place in England, as the international reference. Their Paris meridian was still in use at the beginning of the 20th century and their 'prime meridian' is even mentioned in the book and movie: The Da Vinci Code.

Because of the use of Greenwich reference in nautical tables, the French then wrote in the margin of their mautical charts the difference between Paris and Greenwich. But they soon had go give up.

However they had to keep fighting to have an English name out of the international standard and they recently succeeded: GMT is no longer the proper name of the prime meridian but UTC (Universal time convention) is.

The proper way to tell time today is UTC. For example, I live in Oslo and during our light saving summer time, we are at UTC+2, that is, two hours before the sun meridian at Greenwich.

Note that the aviation notation of Zulu is the same as UTC and GMT. This is in fact an old naming of the time zones, UTC being Zulu; east of that, Alpha, Brave, etc. and west of that Mike, November, etc. Today, only Zulu is kept and the time is written e.g. 12:00z but spoken: twelve hundred UTC in standard Air Traffic Control terminology.

Answer 6

GMT = Greenwich Mean Time, the arbitrary "standard" time picked as a reference when mariners were working on determining longitude .to use as they navigate the globe  Determining longitude is the determining how far you are east or west of a reference by using the position of the sun at high noon. Latitude is EASY, as all you need do is measure the altitude of the Sun at high noon, and then according to an almanac with seasonal changes, determine exactly how north or south you are from the equator. The Earth turns through 360 degrees in a day, which means 15 degrees per hour. So, if I have a timepiece which I set to a reference, GMT in this case, which is highly accurate, and I then travel from Greenwich to any other place on the globe and then mark the time when I see high noon, the difference between local time and my reference timepiece keeping GMT, tells me exactly how far east or west I am relative to Greenwich. The choice of Greenwich was purely arbitrary and was chosen by the maritime interests because it was a convenient observatory to use. Once the timepiece was invented and perfected to keep accurate time, Greenwich held on as the "standard" time for sailors no matter where they were in the world, eventually being used universally by everyone as the reference. Since then, others have taken on the mantle of a "reference" time, the former National Bureau of Standards (now named The National Institute of Standards & Technology - NIST) in Boulder, Colorado, broadcast standard date and time information on shortwave, radio station WWV, on 5, 10, 15, 20 and 25 MHZ. By the way, though located in Boulder, CO, they do NOT tell you local time, but the time in GREENWICH! The frequencies are a reference standard as well as the signals. You could calibrate a local oscillator by doing a zero beat against WWV. You still CAN, but now they call it Coordinated Universal Time instead of GMT, but it is STILL the time in Greenwich, no matter WHAT they call it these days. By the way, the "reference" time, whichever you choose to use does NOT shift an hour in spring and fall. GMT does not change, but the time zone Greenwich is in DOES. It is the time zone which changes, NOT the standard time used by mariners and others as a time reference. The sun has no idea what we do with the indicated time, high noon is high noon no matter what the hands of a clock indicate and once I sync my timepiece with Greenwich, I NEVER change it. I look at my timepiece, I mark the local high noon and subtract to tell the difference, and if the zone is on daylight saving time or not has no effect on this determination of longitude as I navigate, and in fact makes it more difficult if I keep track of the zones which use the hour difference. I fail to see the purpose behind daylight saving time. The position of the sun does not change, so why change what time the clocks indicate by an hour to fool us into thinking the day is longer in the evening in summer? Anyway, this is probably too much information, but then I happen to like knowing the history behind things in my life. GMT happens to one of the things I found interesting when I learned how to navigate at sea.

Edit: UTC - quote from wiki entry

Coordinated Universal Time is abbreviated UTC. The International Telecommunication Union wanted Coordinated Universal Time to have a single abbreviation for all languages. English speakers and French speakers each wanted the initials of their respective language's terms to be used internationally: "CUT" for "coordinated universal time" and "TUC" for "temps universel coordonné". This resulted in the final compromise of using "UTC".

Answer 7

Greenwich Mean Time

All other times are based on GMT

Answer 8

Greenwich Mean Time (GMT) is a term originally referring to mean solar time at the Royal Observatory in Greenwich, London. It is now often used to refer to Coordinated Universal Time (UTC) when this is viewed as a time zone, although strictly UTC is an atomic time scale which only approximates GMT in the old sense. It is also used to refer to Universal Time (UT), which is the astronomical concept that directly replaced the original GMT. In the UK, GMT is the official time only during winter; during summer it's British Summer Time.

Noon Greenwich Mean Time is not necessarily the moment when the sun crosses the Greenwich meridian (and reaches its highest point in the sky in Greenwich) because of Earth's uneven speed in its elliptic orbit and its axial tilt. This event may be up to 16 minutes away from noon GMT (this discrepancy is known as the equation of time). The fictitious mean sun is the annual average of this nonuniform motion of the true Sun, necessitating the inclusion of mean in Greenwich Mean Time.

Historically the term GMT has been used with two different conventions for numbering hours. The old astronomical convention (before 1925) was to refer to noon as zero hours, whereas the civil convention during the same period was to refer to midnight as zero hours. The latter is modern astronomical and civil convention. The more specific terms UT and UTC do not share this ambiguity, always referring to midnight as zero hours.