[tz] 1 s error in America/Adak and America/Nome

Michael H Deckers michael.h.deckers at googlemail.com
Mon Jun 12 15:23:38 UTC 2017

On 2017-06-10 21:15, Paul Eggert wrote:

> .... However, the the question is whether America/Sitka should record 
> the time kept by those in formal control of Sitka, or the time kept by 
> Toomas Ahllund and his fellow workers who made the transition on 
> Sunday in order to have a longer weekend. If the former, the 
> transition should be at 15:30 Friday (Gregorian); if the latter, it 
> should presumably be at 00:00 Sunday (Gregorian). I chose the former, 
> partly because it reflects formal transfer of control, and partly 
> because we have a specific time-of-day recorded for it.

       I agree that we need an estimate for the precise instant of the
       jump by 24 h in the Alaskan time scales near 1867-10-18, as
       long as we do not have evidence, such as from port diaries.
       What worries me a bit are the underlying assumptions of the
       new estimate:
       •  an odd time (1867-10-19T00:31:13Z) of a local event in Sitka
          is certainly not the effective time of an international treaty
          like the Alaska purchase;
       •  assumptions that the day of the week was set back from Saturday
          to Friday at 15:30 or at 15:33:32 local time are unlikely to
          be true -- such things are done over night;
       •  the assumption that various remote places in Alaska in 1867, not
          connected by telegraphy lines, would have spent any effort to
          synchronize some of their actions seems unlikely to me. They
          had no reason to do it, and they would have needed several days
          on sea to even agree on the event to be synchronized.
       That is why I prefer the previous estimate: do the switch at some
       local midnight close to the date of the purchase.

       To make this post a bit more productive, here are the implications
       of what the 2001 "Alaska History" [AH] page by Frank Norris says
       about Juneau before 1969:

      Zone America/Juneau      15:02:19 -     LMT     1867 Oct 19 15:33:32
                               -8:57:41 -     LMT     1900 Aug 20 12:00
     # [AH] "The implementation of a telegraph system, in practical terms,
     #       demanded the establishment of one or more time zones, and
     #       given the concentration of economic and political power at
     #       the time in Alaska’s southeastern panhandle, it was 
     #       that “Alaska Standard Time,” established in 1900, would be
     #       centered on the 135th meridian, just one hour before Pacific
     #       Standard Time.(6)
     #       (6) Annual Report of the Governor of Alaska, 1901, 73."
     -                         -8:00  -       PST     1942
     +                         -9:00  -       YST     1933 May 24
     # [AH] "In May 1933, Seattle launched a new daylight saving time 
     #       In reaction, Juneau city council member J. B. Burford 
presented a
     #       daylight saving time petition “signed by many business people.”
     #       ..[T]he council unanimously adopted Burford’s plan, and Juneau
     #       went on daylight saving time from May 24 through September 
     #       (11) Daily Alaska Empire, May 6, 19-20, and 24, 1933 and 
September 20, 1933."
     +                         -9:00  1:00    YDT     1933 Sep 24
     +                         -9:00  -       YST     1940 Apr 30 23:00
     # [AH] "On April 2, 1940, voters in the Juneau-Douglas area adopted the
     #       time-change move on a 753-564 vote, and at 11 p.m. on April 30,
     #       area clocks shifted an hour ahead. Other Southeast communities
     #       apparently followed suit, and by the eve of World War II nearly
     #       all of Southeast, except Skagway and Yakutat, had adopted 
Pacific Time.(13)
     #       13. Daily Alaska Empire, May 20, June 6, and July 6-8 and 
22, 1939, and April 3 and 30, 1940."
     +                         -8:00  -       PST     1942 Feb 09 02:00
     # [AH] "On February 9, 1942, Alaska, along with the other states and
     #       territories, went on daylight saving time or “war time” on a
     #       year-round basis. Because many southeastern communities had 
moved to
     #       Pacific Time in 1940, adopting federally mandated war time 
in those
     #       communities brought no changes to local clocks."
     -                         -8:00  US      P%sT    1946
     +                         -9:00  1:00    YWT     1945 Aug 14 23:00u
     +                         -9:00  1:00    YPT     1945 Sep 30 02:00
                               -8:00  -       PST     1969

     Michael Deckers.

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