[tz] uptodate data

Alois Treindl alois at astro.ch
Thu Nov 14 06:41:26 UTC 2019

On 13.11.19 08:56, Jean wrote:
> @Paul and Matt
> Thanks both for answering.
> @Matt, when i try to update tzdata it says it is already up to date. 
> My impression was that it was not, because of the Morokko 2018 switch. 
> But that assumption seems false. I read you are still debating about 
> Morokko.
> @Paul, it's a long story and an important one for me because many 
> people find it unforgiving if software in my field has errors in it's 
> timezone atlas. Since i discovered the trick with zdump it's a lot 
> better but not perfect. As said, America/Chicago is notorious, over 
> the years i had many reports of wrong timezones there, a notable one 
> is the birth of Dylan, Bob 24 May 1941 21:05:00 Duluth MN, United 
> States, 92w06, 46n47, America/Chicago.
> The timezone as listed on astro.com (they are regarded as the standard 
> just as the people from astrolabe) is 6 
> hours(https://www.astro.com/astro-databank/Dylan,_Bob).
TZ zone America/Chicago covers a large part of the United states and is 
correct for all towns in it, after 1 january 1970.

Before that date, America/Chicago is only sure to be correct for the 
city of Chicago itself, but not for all the other places in the area 
covered by the zone.

In fact, American Atlas by Thomas Shanks, which is the best source for 
pre-1970 time zone history in the US, needs 375 tables to represent all 
the variants of time zone history in this area.

Mostly affected states are IA, IL, IN, KY, MN, MO, ND, NE, OK, TN, WI.

The same is true for America/New_York

Shanks needs 857 different tables to represent time zone history for the 
area covered by the single TZ zone America/New_York after 1 Jan 1970.

Affected states are CT, DE, FL, GA, KY, MA, MD, ME, NC, NH, NJ, NY, OH, 
PA, TN, VA, VT, WV. They all had 'chaotic' time zone before 1967, when 
the Uniform Time Zone act went in force.

It is hard to compute correct horoscopes, I can tell you.

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