Difference between revisions of "30W Time Zone Rule"

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(Add coordinates to test W30 compliance)
imported>Sermoa
m (Testing for 30W compliance: oh i see it's usually called 30W not W30.)
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* Western coordinates
 
* Western coordinates
  
== Testing for W30 compliance ==
+
== Testing for 30W compliance ==
  
 
Here are the geohash coordinates in Greenland around the time of that the W30 rule was introduced. Coordinates rounded to 5 decimal places. You can use this to confirm that your application produces the right coordinates.
 
Here are the geohash coordinates in Greenland around the time of that the W30 rule was introduced. Coordinates rounded to 5 decimal places. You can use this to confirm that your application produces the right coordinates.

Revision as of 12:49, 2 January 2010

Announced Saturday, May 24, 2008 03:34 UTC

There’s been a small change to the algorithm to deal with time zones. This change does not affect anyone in North/South America (excluding eastern Greenland), does not affect Saturday meetup times anywhere, and does not change any currently known upcoming meeting times. The change:

For every location east of Longitude -30 (Europe, Africa, Asia, and Australia), 
use the Dow opening from the previous day — even if a new one becomes available 
partway through the day.

Put differently (the same functionally for everywhere except islands in the mid-Atlantic):

Consider any Dow openings published after noon local time 
to have occurred on the next day.

This is necessary to deal with time zone problems. For a lot of Europe, the Wednesday Dow opening was learned near sundown Wednesday, which meant they couldn’t use it to get to daytime meetups. For east Asia, they had to visit weekday locations the next day. A bunch of solutions were discussed, and I decided this was the cleanest.

The map program has been updated with this rule. The first coordinates that will be affected by it are for Tuesday, May 27, 2008. Again, this does not affect anyone in the Americas.

Implementations

Authors of existing implementations are encouraged to update them before 12:00 UTC on Monday, May 26 so that your users in the easternmost time zones can have a smooth transition. Once updated, add {{30w compliant|yes=1}} to the Implementations page.

Announcement Templates

In affected areas (east of -30° longitude), please add {{pre30w}} to old expedition pages from May 21-23, 2008. (May 24-26 are unaffected due to the weekend and the Dow holiday for Memorial Day.)

Terminology

The following terms may be found referring to the adjusted coordinates for locations east of W30:

  • W30 adjusted coordinates
  • W30 coordinates
  • Eastern coordinates

Coordinates for those locations west of W30 may be found using these terms:

  • Non-W30 coordinates
  • Western coordinates

Testing for 30W compliance

Here are the geohash coordinates in Greenland around the time of that the W30 rule was introduced. Coordinates rounded to 5 decimal places. You can use this to confirm that your application produces the right coordinates.

Date Dow Jones Hash string Hash string east of W30 Coordinates 68, -31 Coordinates 68, -30 Coordinates 68, -29
2008-05-20 13026.04 2008-05-20-13026.04 2008-05-20-13026.04 68.63099, -31.61895 68.63099, -30.61895 68.63099, -29.61895
2008-05-21 12824.94 2008-05-21-12824.94 2008-05-21-12824.94 68.17947, -31.86154 68.17947, -30.86154 68.17947, -29.86154
2008-05-22 12597.69 2008-05-22-12597.69 2008-05-22-12597.69 68.97287, -31.2387 68.97287, -30.2387 68.97287, -29.2387
2008-05-23 12620.90 2008-05-23-12620.90 2008-05-23-12620.90 68.40025, -31.72277 68.40025, -30.72277 68.40025, -29.72277
2008-05-24 12620.90 2008-05-24-12620.90 2008-05-24-12620.90 68.12665, -31.54753 68.12665, -30.54753 68.12665, -29.54753
2008-05-25 12620.90 2008-05-25-12620.90 2008-05-25-12620.90 68.94177, -31.18287 68.94177, -30.18287 68.94177, -29.18287
2008-05-26 12620.90 2008-05-26-12620.90 2008-05-26-12620.90 68.67313, -31.60731 68.67313, -30.60731 68.67313, -29.60731
2008-05-27 12479.63 2008-05-27-12479.63 2008-05-27-12620.90 68.20968, -31.10144 68.20968, -30.10144 68.12537, -29.57711
2008-05-28 12542.90 2008-05-28-12542.90 2008-05-28-12479.63 68.68745, -31.21221 68.68745, -30.21221 68.71044, -29.11273
2008-05-29 12593.87 2008-05-29-12593.87 2008-05-29-12542.90 68.4647, -31.03412 68.4647, -30.03412 68.27833, -29.74114
2008-05-30 12647.36 2008-05-30-12647.36 2008-05-30-12593.87 68.8531, -31.2446 68.8531, -30.2446 68.32272, -29.70458

See also