john@ektools.UUCP (John H. Hall) (03/02/88)
Ok, so GMT is now called UTC or "Universal Coordinated Time". As a
pilot, I know that aviation weather reports, flight plans, and a whole
bunch of other such things are reported in "Zulu time", where "Zulu"
is the ICAO phonetic alphabet's letter "Z". Times are written with a
"Z" suffix, as in "0830Z". Zulu time is EST+5 and EDT+4 (Your
timezones may vary. Half an hour earlier in Newfoundland). Is Zulu
time just another expression of UTC?
Another question about UTC. Does it run from 0000 to 2359, or from
0001 to 2400? What is the UTC at midnight (in Greenwich)?
--
John Hall, Supervisor: Software Tools Group, Product Software Engineering
EASTMAN KODAK COMPANY, 901 Elmgrove Rd., Rochester, NY 14650, 716 726-9345
UUCP: {allegra, rutgers}!rochester!kodak!ektools!john
ARPA: kodak!ektools!john@rochester.ARPAfktsun@violet.waterloo.edu (Frankie Kim-Tak Sun) (03/04/88)
In article <1083@ektools.UUCP>, john@ektools.UUCP (John H. Hall) writes: > ..."Z" suffix, as in "0830Z". Zulu time is EST+5 and EDT+4 (Your > timezones may vary. Half an hour earlier in Newfoundland). Is Zulu > time just another expression of UTC? > > Another question about UTC. Does it run from 0000 to 2359, or from > 0001 to 2400? What is the UTC at midnight (in Greenwich)? Yes, Zulu time is the same as UTC(Coordinated Universal Time, rather than Universal Coordinated Time), although I think Zulu time is the term used most often in aviation and the military?, while the other one is more popular among scientific applications. UTC runs from 0000 to 2359. Therefore, using this convention, midnight UTC is denoted as 0000. Frankie Sun fktsun@violet.waterloo.edu
jra@jc3b21.UUCP (Jay R. Ashworth) (03/06/88)
From article <1083@ektools.UUCP>, by john@ektools.UUCP (John H. Hall): > Ok, so GMT is now called UTC or "Universal Coordinated Time". As a > pilot, I know that aviation weather reports, flight plans, and a whole > bunch of other such things are reported in "Zulu time", where "Zulu" > is the ICAO phonetic alphabet's letter "Z". Times are written with a > "Z" suffix, as in "0830Z". Zulu time is EST+5 and EDT+4 (Your > timezones may vary. Half an hour earlier in Newfoundland). Is Zulu > time just another expression of UTC? Yes. > Another question about UTC. Does it run from 0000 to 2359, or from > 0001 to 2400? What is the UTC at midnight (in Greenwich)? Both. 0000=2400, but 0000 is associated with today's UTC date, while 2400 is assoicated with yesterday's. Generally, "Zulu" is a phonetic expression of "Z", the code for this time zone. All the time zones in the world have a one-letter identifier. The one for Grenwich happens to be "Z". Anyone interested in time might want to write to the NBS, Radio Station WWV, as they have several standard publications about the subject. Unfortunately, I don't have Pub. #'s for this stuff, but they might send you a list... National Bureau of Standards radio Station WWV 200 E. County Rd. 58 Ft Collins CO 80302 -- jra, KA1FJX > > -- > John Hall, Supervisor: Software Tools Group, Product Software Engineering > EASTMAN KODAK COMPANY, 901 Elmgrove Rd., Rochester, NY 14650, 716 726-9345 > UUCP: {allegra, rutgers}!rochester!kodak!ektools!john > ARPA: kodak!ektools!john@rochester.ARPA -- Jay R. Ashworth ---+-- The Great Ashworth & ------------+ ...!uunet!codas! 10974 111th St. N. | Petrillo Production Company | !usfvax2!jc3b21!jra Seminole FL 34648 +-- Gonna hafta face it, I'm addicted to news...-+--------- (813) 397-1859 ----+-- Tampa Bay's Smallest Video Production House -+ :-) !$
msb@sq.uucp (Mark Brader) (03/11/88)
> All the time zones in the world have a one-letter > identifier. The one for Greenwich happens to be "Z". This would be a neat trick, since there are about 35 time zones in the world. Even when you exclude the ones that are on half hours and odder amounts, there are still at least 26, because the International Date Line wanders east and west. Does the single-letter system cover all of these? What does it do about daylight saving time, which creates an additional "zone" just west of the line when in effect? Mark Brader "I will be speaking today about work in progress, SoftQuad Inc. instead of completed research; this was not my Toronto intention when I chose the subject of this lecture, utzoo!sq!msb but the fact is I couldn't get my computer programs msb@sq.com working in time." -- D.E. Knuth
dick@slvblc.UUCP (Dick Flanagan) (03/13/88)
In article <1988Mar11.014836.4816@sq.uucp> msb@sq.uucp (Mark Brader) writes: > > All the time zones in the world have a one-letter > > identifier. The one for Greenwich happens to be "Z". > > This would be a neat trick, since there are about 35 time zones in the world. Well, there are really only 25 "official" time zones around the world. Generally one for each hour of the earth's rotation each day. With two exceptions, each is 15 degrees of longitude (or one hour) wide. Each is given a letter designation. 'J' is omitted (I've often wondered who decides such things) and 'Z' straddles the Prime Meridian through Green- wich, England. The two exceptions are the 'M' and 'Y' zones which are only 7-1/2 degrees wide and which are on either side of the International Date Line. Whereas the time difference in both zones is the same--12 hours--one is a positive difference and the other is negative. > Even when you exclude the ones that are on half hours and odder amounts, > there are still at least 26, because the International Date Line wanders > east and west. Does the single-letter system cover all of these? Obviously not (see below). > What does it do about daylight saving time, which creates an additional > "zone" just west of the line when in effect? Daylight saving times, wandering date/time lines, and the like are social phenomena, not physical ones. Dick -- Dick Flanagan, W6OLD GEnie: FLANAGAN UUCP: ...!ucbvax!ucscc!slvblc!dick Voice: +1 408 336 3481 Internet: slvblc!dick@ucscc.UCSC.EDU LORAN: N037 04.7 W122 04.6 USPO: PO Box 155, Ben Lomond, CA 95005