Time-zone Atlas • Find Birth Town • Horoscope of the Moment
About the Astrodienst Atlas
Geographical Data
The geographical data, i.e., locations with their geographical coordinates, come from various public sources:
- Public Domain Database www.geonames.org
- from the two books The American Atlas (1996) and The International Atlas, 6th edition (2006), by Thomas G. Shanks, published by Astro Communications Inc.
- Data collected by Astrodienst, since 1980
Time Zone Data
The following map shows the approximately 400 zones contained in the public TZ database (version 2023d).
The current and historical information on time zones and daylight saving times comes from
- the public domain database TZ, see Wikipedia TZ Database, especially for data from 1970 onwards.
- American astrologer Doris Chase Doane published three reference books Time Changes in the U.S.A (1966, revised 1980), Time Changes in Canada and Mexico (1968, revised 1986), Time Changes in the World (1971, revised 1982).
- from the two books The American Atlas (1996) and The International Atlas, 6th edition (2006), by Thomas G. Shanks, published by Astro Communications Inc., only for data before 1970, an important source for the irregular use of daylight saving time in various Canadian and US states before its national standardization.
- Time zone information from the books Traité de l'heure dans le monde, by Gabriel (1990), Régimes Horaires pour l'Europe et l'Afrique, by Henri Le Corré (1982), L'astrologie confrontée aux régimes des zones occupied en France de 1914 à 1945, Guy Mayeres (2006), Новый справочник астролога. Координаты городов и временные поправки (A new astrologer's reference book. Coordinates of cities and time corrections), Zaitsev A., Kutalev D. (2015), and others.
- Research and data collection by Alois Treindl since the founding of Astrodienst in 1980, some of which have also been included in the public TZ database. The most important primary sources for research are newspaper archives, old airport data, and train timetables.
Rules for using the service
The Astrodienst server is a reference source for private use by astrologers. It is not allowed to build a commercial service based on the resources of this server, or to extract the information in this server systematically for data capture.If our system detects an excessive number of requests from the same source within a certain period of time, it will automatically refuse further access.
No Atlas Access via Software
The Astrodienst server is intended to be used by human individuals, who use an Internet browser interactively to connect to our server and type their queries by hand. Automatic access by query-generating software is not acceptable and will be considered illegal. Should we be able to identify that from some connections automatic queries are arriving, we block the Internet address groups which are the source of such queries.
Some developers
of astrological software may have the plan to build
automatic access to this server into their programs. This would
allow them to offer complete city and timezone information in their
software without having to make any effort, just by sending a few
URLs over the Internet.
How well is pre-1970 time zone history represented in TZ database?
(published by Alois Treindl on 3 June 2020 in TZ mailing list).
It is known that pre-1970 time zone history is represented in TZ database only for the cities which define the zone names. Other areas of countries are often not correctly represented in TZ database before 1970.
The worst are the USA and Canada, because there, in many states, the authority about daylight time adherence was in the hands of counties or towns, up to the Uniform Timezone Act of 1967.
I am personally responsible for providing correct timezone history for the astrological service company Astrodienst AG in Switzerland, which runs among other things the website www.astro.com
As source for timezone history we use, besides TZ database, the International and American Atlas by Thomas Shanks, and our own research.
The data we have are still far from perfect, because many local details of time zone and daylight saving time use are unknown, especially in the US and Canada.
We have about 25 million birth data records in our database.
I have analyzed to what extent TZ database represents the time zone information correctly, for these data.
I think the results are of some interest for the TZ community.
The overall sums are:
tz_count 24'674'767 data records, 100% tz_irange 23'675'636 in time range and region which TZ covers correctly, 96% tz_good 736'769 in time range and region where TZ is unreliable, but correct, 3% tz_bad 262'362 in time range and region where TZ database gives false result. 1%This means that only 1% of our astrological charts would be false, if we used TZ database only, without any extra time zone history sources.
More details by country or US/Canada state. state count in_range % good % bad % USA AK (US) 19889 99.6 0.0 0.3 Alaska AL (US) 64975 78.6 13.3 8.1 Alabama AR (US) 43159 77.2 12.7 10.0 Arkansas AZ (US) 96545 97.9 2.0 0.0 Arizona CA (US) 981941 100.0 0.0 0.0 California CO (US) 107204 99.5 0.5 0.0 Colorado CT (US) 89273 95.8 4.2 0.0 Connecticut DC (US) 58401 85.7 13.1 1.1 District of Columbia DE (US) 14376 91.3 8.5 0.3 Delaware FL (US) 241083 89.0 6.5 4.5 Florida GA (US) 114613 85.8 7.1 7.2 Georgia (US) HI (US) 44070 100.0 0.0 0.0 Hawaii IA (US) 50194 72.7 17.1 10.2 Iowa ID (US) 23877 92.2 6.4 1.4 Idaho IL (US) 267459 90.4 9.5 0.1 Illinois IN (US) 88263 76.8 21.6 1.6 Indiana KS (US) 45462 74.4 15.0 10.6 Kansas KY (US) 56494 74.6 12.5 12.9 Kentucky LA (US) 76017 80.3 11.9 7.8 Louisiana MA (US) 193439 87.1 12.9 0.1 Massachusetts MD (US) 91577 91.2 8.1 0.7 Maryland ME (US) 31873 96.8 2.8 0.5 Maine MI (US) 185568 86.0 13.3 0.7 Michigan MN (US) 95725 75.0 17.0 7.9 Minnesota MO (US) 91038 79.4 14.4 6.2 Missouri MS (US) 28859 70.0 20.4 9.6 Mississippi MT (US) 19767 73.7 24.7 1.5 Montana NC (US) 106991 82.9 10.2 6.9 North Carolina ND (US) 12427 71.5 17.5 10.9 North Dakota NE (US) 28670 69.1 18.2 12.7 Nebraska NH (US) 23707 91.2 8.2 0.6 New Hampshire NJ (US) 190614 99.6 0.3 0.1 New Jersey NM (US) 42651 80.6 18.4 0.9 New Mexico NV (US) 36053 99.4 0.4 0.3 Nevada NY (US) 628944 96.8 3.0 0.1 New York OH (US) 191745 73.9 18.3 7.8 Ohio OK (US) 55229 73.7 16.5 9.8 Oklahoma OR (US) 98166 87.1 9.8 3.1 Oregon PA (US) 228064 89.8 9.7 0.6 Pennsylvania PR (US) 37149 100.0 0.0 0.0 Puerto Rico RI (US) 26089 97.1 2.8 0.1 Rhode Island SC (US) 40233 82.9 10.0 7.1 South Carolina SD (US) 12863 72.7 18.6 8.7 South Dakota TN (US) 75125 82.9 9.3 7.8 Tennessee TX (US) 327328 83.3 9.8 6.9 Texas UT (US) 48909 82.7 16.2 1.1 Utah VA (US) 109591 85.5 10.1 4.4 Virginia VT (US) 17598 86.4 12.7 0.9 Vermont WA (US) 159835 84.8 11.9 3.3 Washington WI (US) 85917 75.5 18.5 5.9 Wisconsin WV (US) 22800 72.7 20.3 7.0 West Virginia WY (US) 8962 75.1 23.9 0.9 Wyoming Canada AB (CAN) 64249 97.9 2.0 0.1 Alberta BC (CAN) 99214 98.0 2.0 0.0 British Columbia (CAN) MB (CAN) 21563 69.8 27.5 2.6 Manitoba (CAN) NB (CAN) 10438 89.0 8.3 2.7 New Brunswick (CAN) NF (CAN) 7329 98.4 1.2 0.4 Newfoundland (CAN) NS (CAN) 18829 75.4 16.3 8.2 Nova Scotia (CAN) NT (CAN) 1137 80.7 0.0 19.3 Northwest Territories (CAN) ON (CAN) 239755 86.3 12.4 1.3 Ontario (CAN) PE (CAN) 2036 80.0 16.1 3.9 Prince Edward Island (CAN) QU (CAN) 126300 88.4 9.8 1.8 Quebec (CAN) SK (CAN) 24390 78.2 12.4 9.5 Saskatchewan (CAN) YK (CAN) 932 100.0 0.0 0.0 Yukon Territories (CAN) Other countries with significant issues in TZ database, only those with > 1% bad results BY 13966 97.1 1.2 1.7 Belarus CAR 268 33.2 0.4 66.4 Central African Repub CHINA 214617 96.0 2.4 1.6 China CONGO 1026 49.9 0.0 50.1 Congo (Brazaville) GABON 704 47.7 0.0 52.3 Gabon GUAM 3613 45.6 0.0 54.4 Guam INDSA 51950 97.2 0.8 2.0 Indonesia NIGER 294 76.9 3.7 19.4 Niger NIRE (UK) 16228 97.1 0.7 2.1 Northern Ireland RU 177880 89.4 8.5 2.1 Russian Federation SUDAN 2495 0.0 0.0 100.0 Sudan (?? my be my fault) TAAF 2 0.0 0.0 100.0 French Kerguelen Islands TANZ 4162 68.3 30.2 1.5 Tanzania TOK 17 41.2 0.0 58.8 Tokelau UA 71260 95.9 2.4 1.7 Ukraine VIET 299630 97.6 0.8 1.6 Vietnam
Comment on 4 June 2025: The situation has probably improved since 2020, because the user base gets younger and a lower percentage of users is born before 1970 in the problematic states of USA and Canada.
