Changes: Time Zone Conversion

Latest revision as of 11:28, 22 December 2014

Folders come from all over the world, and therefore live in every conceivable time zone. On this page you will find a number of coder / decoder charts that should help you to translate from your local time into Coordinated Universal Time (UTC). The foldit site uses UTC for a variety of purposes, e.g. puzzle expiry times. Folders on a team might also use a UTC time, e.g. in the description of a shared solution to document when it was submitted.

Simple time converter from Time and Date Shows the time in all the main cities around the world, just input the date and time of the event.

Hour Aliases[]

The charts are be based on Hour Aliases, a series of aliases (synonyms) for the twenty four hours 12AM, 1AM, ..., 11AM, 12PM, 1PM, ..., 11PM. Besides the twenty-four hour clock hours 00, 01, ..., 22, 23; we will use 24 letters as follows: Z, A, B, C, ..., W (Z for "zero", A for "one", etc.). The letters will sometimes be expanded to their equivalent Nato Phonetic Alphabet telephony codes: Zulu, Alfa, Bravo, Charlie, ... Whiskey.

Zone Zulu chart[]

The Zone Zulu chart has the 24 single letter hour aliases (Z, A, B, ..., W) placed on an analog clock face with the AM letters in an inner ring, the PM letters in an outer ring. Should you be looking at the hands of an analog clock set to Coordinated Universal Time (UTC), a four character "Zulu" time ammZ can be directly read from the chart. For example, if the hands show midnight, that's Z00Z, which is equivalent to 0000Z, 00:00 UTC, 12AM Z, 12AM Zulu and so on. If it's afternoon and the analog "little hand" is pointing as it would for 4PM and the little hand is pointing as it would for 35 minutes past the hour, the ammZ code would be P35Z, 16:35 UTC and so on.

Conversion charts by time zone[]

Folders in time zones with exact hour offsets from UTC can find their offset and load their proper conversion chart from the following table:

Conversion chart by time zone -- UTC offset
Time Zone	Conversion Chart	Time Zone	Conversion Chart
UTC+/-00:00	Zone Zulu	UTC-01:00	Zone Alfa
UTC+01:00	Zone Whiskey	UTC-02:00	Zone Bravo
UTC+02:00	Zone Victor	UTC-03:00	Zone Charlie
UTC+03:00	Zone Uniform	UTC-04:00	Zone Delta
UTC+04:00	Zone Tango	UTC-05:00	Zone Echo
UTC+05:00	Zone Sierra	UTC-06:00	Zone Foxtrot
UTC+06:00	Zone Romeo	UTC-07:00	Zone Golf
UTC+07:00	Zone Quebec	UTC-08:00	Zone Hotel
UTC+08:00	Zone Papa	UTC-09:00	Zone India
UTC+09:00	Zone Oscar	UTC-10:00	Zone Juliett
UTC+10:00	Zone November	UTC-11:00	Zone Kilo
UTC+11:00	Zone Mike	UTC+/-12:00	Zone Lima

Note that for the purposes of table lookup UTC+13:00 is the same as UTC-11:00, UTC-14:00 is the same as UTC+10:00, and so on.

Suppose Alice is at the University of Washington at Seattle, WA, (where foldit is based) and it's December 13th. Alice sees that she's under US Pacific Standard Time, which is UTC-08:00, so she brings up the conversion chart for Zone Hotel. It's 8:10PM, so she examines the chart, finding that the 8 O'Clock spot on the PM (outer) ring reads "D", so her ammZ code for the present time is D10Z, or 04:10 UTC. Since on the chart she is after time "Z" and before her local midnight, she adds one day, making it December 14th. She could then use a short time stamp like 12/14 D10Z or 12/14 0410Z to report the "Zulu" time.

Note on time zones with part hour offsets[]

Some time zones have offsets from UTC that are not whole hours. For example, Canadian Newfoundland Daylight Time is UTC-02:30. If Bob is reporting times in this zone, he can use Zone Charlie, but his own time is 30 minutes ahead of this. Therefore, he will have to subtract 30 minutes from his clock time before he reports his Zulu time. Similarly, he could use Zone Alfa, but his own time is 30 minutes behind that. So if he's using Zone Alfa he will have to add 30 minutes before he reports his Zulu time.

Discussion[]

The idea for the conversion charts came from reading the book Time Lord (2000), by Clark Blaise, a biography of time zones pioneer of Sandford Fleming. His original proposal for universal time included letter-coded hours, but omitting "I" and "U". Nautical time does something similar with the zones. I thought using A-W to represent 01-23 was a bit more natural. Z for 00 seems well established. In the system presented here, local midnight (and the negative offset from Z) for each zone is the same as the zone's letter designator.

Since we're generally not very interested in solar times in Greenwich England, it's not actually necessary to consider the actual values for the single letter codes for the hours. For example, when I'm under Canadian Atlantic Standard Time (UTC-4), I don't really care that "S" is valued at "19". Instead, I see that "S" lies at the 3PM slot on the Zone Delta conversion slot, meaning that if it's 3PM local time for me, I can report that time as S00Z.

In fact, removing the letters from their numeric meaning might serve to make it easier to code and decode the ammZ times.

Chart Photos[]

Zones Alfa through Zulu photos

@@ Line 1: / Line 1: @@
 Folders come from all over the world, and therefore live in every conceivable [http://en.wikipedia.org/wiki/Time_zone time zone].  On this page you will find a number of coder / decoder charts that should help you to translate from your local time into [http://en.wikipedia.org/wiki/Coordinated_Universal_Time Coordinated Universal Time (UTC)].  The [http://fold.it/portal/ foldit site] uses UTC for a variety of purposes, e.g. puzzle expiry times.  Folders on a team might also use a UTC time, e.g. in the description of a shared solution to document when it was submitted.
+[http://www.timeanddate.com/worldclock/fixedform.html Simple time converter from Time and Date] Shows the time in all the main cities around the world, just input the date and time of the event.
 ==Hour Aliases==