Chinese timezones

[Paul Eggert]

Jesper Norgaard Welen <jnorgard at prodigy.net.mx> writes:

> it is the historic timezones that interest me, while the current
> division of China in only one timezone is rather trivial. The idea
> is to be able to calculate what was the local time in Harbin or
> Lishui when it was 10:15:00 GMT 14.th. of August 1941 (as an
> example). And no, the answer is surely not 18:15:00!

For that sort of thing the Shanks & Pottenger database is the best
that I know of, though of course it's not infallible.  They do attempt
to cover the wartime changes.  Shanks was born during Eastern War Time
and notes this fact in the author's bio on his book.

You should be able to determine the zone boundaries yourself, if you
have good maps, by consulting the Atlas Query
<http://www.astro.com/cgi/aq.cgi>, which is an online version of the
Shanks & Pottenger database.  For example, I just verified that
according to that database, Harbin was at UTC+0830 on 1970-01-01
00:00.  As far as I know, the only post 1970 change in China was in
May 1980, so if you use any time stamp from 1970 to 1980 you should be
able to wander around the Chinese countryside using that database and
determine where the time zone boundaries were.  (Good luck with the
spellings, though!)

> (Paul, your email was more helpful than the tz
> database itself!).

Yes, I had started to update 'asia' when I answered your email.
Here's its current (incomplete) state.

--- asia	2006/05/01 13:44:41	2006.6
+++ asia	2006/06/24 21:29:46
@@ -220,6 +220,7 @@ Rule	PRC	1987	1991	-	Apr	Sun>=10	0:00	1:
 # historic timezones from some Taiwan websites.  And yes, there are official
 # Chinese names for these locales (before 1949):
 # Changbai Time ("Long-white Time", Long-white = Heilongjiang area)
+# Heilongjiang, Jilin
 Zone	Asia/Harbin	8:26:44	-	LMT	1928 # or Haerbin
 			8:30	-	CHAT	1932 Mar # Changbai Time
 			8:00	-	CST	1940
@@ -227,10 +228,12 @@ Zone	Asia/Harbin	8:26:44	-	LMT	1928 # or
 			8:30	-	CHAT	1980 May
 			8:00	PRC	C%sT
 # Zhongyuan Time ("Central plain Time")
+# most of China
 Zone	Asia/Shanghai	8:05:52	-	LMT	1928
 			8:00	Shang	C%sT	1949
 			8:00	PRC	C%sT
 # Long-shu Time (probably due to Long and Shu being two names of that area)
+# east Gansu, Guangxi Zhuang, Guizhu, Ningxia Hui, Sichuan, Yunnan
 Zone	Asia/Chongqing	7:06:20	-	LMT	1928 # or Chungking
 			7:00	-	LONT	1980 May # Long-shu Time
 			8:00	PRC	C%sT