GeoNames Forum

I suppose for the most part, they can be derived from country codes.
For the countries with multiple zones, using the admin codes might work.
I guess they could be put into the admin codes table.

For some countries even first administrative divisons can have different time zones, notably the US:
http://home-4.tiscali.nl/~t876506/Multizones.html

For the US time zone shape data is available for download :
http://nationalatlas.gov/mld/timeznp.html

I dont' know whether admincode2 would be sufficient. Would you like to delve into this topic and contribute to it?

Marc

Admittedly I forgot about places like that!

Ultimately you would have to resolve some records by using shape files.
I found some global ones here: (big question mark over distribution!)

http://fri.sfasu.edu/data/geographic/world/shape/
or http://fri.sfasu.edu/data/geographic/world/zip/
(country,time zone,primary admin,etc.,etc.. copyright=uncertain).

ERSI
http://www.esri.com/
(viewer,documentation of file format,etc.)

See also http://www.earthtools.org/ which have a timezone webservice, no idea where the data is sourced and/or how accurate it is.

the update is running right now and the timezone info will be available in the dump as of tomorrow.
We use the timezoneids from the time zone database (tz) :
http://www.twinsun.com/tz/tz-link.htm

For countries with a single timezone we directly use the tz database. For the US we use the shape files from the USGS to find the gmt offset and then we get the closest time zone within this gmt offset. For all others we use the shapes from the Forest Resources Institute to find the gmt offset and then we get the closest time zone within this gmt offset.

Marc

Great work. I didn't expect anything so soon!

Thanx for incuding time zones Marc!

It would be really helpful if apart from the zone name (ex Europe/Athens) you could provide the actual time offset from GMT (ex +2). Also there is an issue with summer time, since some countries use it and others don't. In order to help I have created a list with time offsets and summer times (where applicable) for all countries (source: worldtimezone.com). I hope you find it useful.

http://users.hol.gr/~petrosv/Temp/timezones.xls

Hi petros

Thanks for the list. I did not include GMT offset and DST as I fear it is a little bit too complex to be expressed in a single column. An other reason is I am a java programmer and all you need in java is the name of the timezone, the GMT/DST rules are included in java and you don't have to bother about it.
If we provide a list then it should have the same time zone names we use in the download. Do you think it makes sense to create a list with GMT offset? And for the DST is it sufficient to give the offset without dates and years?

Regards

Marc

Here the data for Greece from http://www.twinsun.com/tz/tz-link.htm :

Code:

 # Greece
 # Rule  NAME    FROM    TO      TYPE    IN      ON      AT      SAVE    LETTER/S
 # Whitman gives 1932 Jul 5 - Nov 1; go with Shanks & Pottenger.
 Rule    Greece  1932    only    -       Jul      7      0:00    1:00    S
 Rule    Greece  1932    only    -       Sep      1      0:00    0       -
 # Whitman gives 1941 Apr 25 - ?; go with Shanks & Pottenger.
 Rule    Greece  1941    only    -       Apr      7      0:00    1:00    S
 # Whitman gives 1942 Feb 2 - ?; go with Shanks & Pottenger.
 Rule    Greece  1942    only    -       Nov      2      3:00    0       -
 Rule    Greece  1943    only    -       Mar     30      0:00    1:00    S
 Rule    Greece  1943    only    -       Oct      4      0:00    0       -
 # Whitman gives 1944 Oct 3 - Oct 31; go with Shanks & Pottenger.
 Rule    Greece  1952    only    -       Jul      1      0:00    1:00    S
 Rule    Greece  1952    only    -       Nov      2      0:00    0       -
 Rule    Greece  1975    only    -       Apr     12      0:00s   1:00    S
 Rule    Greece  1975    only    -       Nov     26      0:00s   0       -
 Rule    Greece  1976    only    -       Apr     11      2:00s   1:00    S
 Rule    Greece  1976    only    -       Oct     10      2:00s   0       -
 Rule    Greece  1977    1978    -       Apr     Sun>=1  2:00s   1:00    S
 Rule    Greece  1977    only    -       Sep     26      2:00s   0       -
 Rule    Greece  1978    only    -       Sep     24      4:00    0       -
 Rule    Greece  1979    only    -       Apr      1      9:00    1:00    S
 Rule    Greece  1979    only    -       Sep     29      2:00    0       -
 Rule    Greece  1980    only    -       Apr      1      0:00    1:00    S
 Rule    Greece  1980    only    -       Sep     28      0:00    0       -
 # Zone  NAME            GMTOFF  RULES   FORMAT  [UNTIL]
 Zone    Europe/Athens   1:34:52 -       LMT     1895 Sep 14
                         1:34:52 -       AMT     1916 Jul 28 0:01     # Athens MT
                         2:00    Greece  EE%sT   1941 Apr 30
                         1:00    Greece  CE%sT   1944 Apr  4
                         2:00    Greece  EE%sT   1981
                         # Shanks & Pottenger say it switched to C-Eur in 1981;
                         # go with EU instead, since Greece joined it on Jan 1.
                         2:00    EU      EE%sT

marc wrote:

If we provide a list then it should have the same time zone names we use in the download. Do you think it makes sense to create a list with GMT offset? And for the DST should is is sufficient to give the offset without dates and years?
[/code]

This is exactly what I had in mind.
A simple list with GMT and DST offsets according to the time zone names you use in geonames would be just great. Thanks!
Dates for DST sound (and look) complicated. A simple offset number should be sufficient.

Cheers,
Petros

Hi Petros

There is now a file called timeZones.txt in the dump directory :

http://download.geonames.org/export/dump/timeZones.txt

It contains all timezoneIds used in the geonames database and for every time zone the gmt offset on January 1st 2006 and the dst offset on 1st July 2006.

Regards

Marc

This is great Marc. Thanx a million!

That was me, Petros. Forgot to log in ...

Hi All,
I created a login to help you out with who I am & remembered to use it
(I'm the thread's poster btw).
I'm glad to see someone else joining in here.
Since my last post on 09/08/2006, I haven't had much time to look back.

It would be nice to see the GMT offset (+ DST as well) included in some webservice results too.
I expect not everyone would need it, so it probably needs only to be in 1 or 2 of the longer 'style' types.

Hi

The search service now has two xml attributes dstOffset and gmtOffset for the timezone element with the FULL style.
http://ws.geonames.org/search?q=london&style=full&maxRows=10

Marc

Anonymous wrote:

Admittedly I forgot about places like that!

Ultimately you would have to resolve some records by using shape files.
I found some global ones here: (big question mark over distribution!)

http://fri.sfasu.edu/data/geographic/world/shape/
or http://fri.sfasu.edu/data/geographic/world/zip/
(country,time zone,primary admin,etc.,etc.. copyright=uncertain).

ERSI
http://www.esri.com/
(viewer,documentation of file format,etc.)

----

those sfasu.edu sites are offline, but the Wayback Machine will retrieve all the content for you.

Hi,

Is it also possible to retrieve the timezone from the latitude and longitude? A webservice that returns the timezone offset for a given latitude/longitude in JSON format would be very welcome!

Cheers,

Steven

Hi Steven

No Problem. Here it is :
http://ws.geonames.org/timezoneJSON?lat=47&lng=8

gmtOffset is on 1. Jan and
dstOffset is on 1. July

Regards

Marc

Thanks Marc! I have two additional questions:

Does this service also supports a parameter called 'callback'?

Why doesn't the service always return the right gmt offset? For every place in Canada for example, it returns -3.5. Also, Australia and Russia give problems.

Steven

Hi Steven

There was a silly bug in the code. It should now work fine. Let me know if you find other problems (I don't hope so).

All JSON services support the 'formatted' (pretty printing) and 'callback' parameters :

http://ws.geonames.org/timezoneJSON?lat=-31&lng=116&formatted=true
http://ws.geonames.org/timezoneJSON?lat=-31&lng=150&callback=timezone

Regards

Marc

Open Ocean Timezones?

Are there any plans (hint hint!) to add support for open ocean timezones?

e.g.

http://ws.geonames.org/timezone?lat=11&lng=-156

In addition- it looks like you've possibly got a bug near the Hawaiian islands:

http://ws.geonames.org/timezone?lat=21&lng=-156

should return something I think. Its not that far from land.

(thanks for an incredible service!)