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I have personally been involved in fallout from last-minute changes to DST in * Jordan * Russia * Armenia * Turkey Morocco suspends DST during Ramadan. Bec

I have personally been involved in fallout from last-minute changes to DST in * Jordan * Russia * Armenia * Turkey Morocco suspends DST during Ramadan. Because legally you cannot predict the start and end of Ramadan (it's determined by direct observation) this is quite the challenge to handle.

signal11 5y ago
For people wondering why Morocco has DST (which isn’t that useful for countries relatively close to the equator?), it seems Morocco chose to permanently become UTC+1 in 2018, with the exception of Ramadan, when it’s UTC. So it’s not really DST in the summer months as done in Europe. Although the Moroccan approach makes for an interesting technical challenge!
- shagie 5y ago
  Searching for Ramadan in https://github.com/eggert/tz/blob/main/asia https://github.com/eggert/tz/blob/main/asia and https://github.com/eggert/tz/blob/main/africa https://github.com/eggert/tz/blob/main/africa is an interesting read. Morocco textual history is at https://github.com/eggert/tz/blob/main/africa#L628 https://github.com/eggert/tz/blob/main/africa#L628 and the implementation rules are at https://github.com/eggert/tz/blob/main/africa#L903 https://github.com/eggert/tz/blob/main/africa#L903 Just above that is this bit: # From Paul Eggert (2020-05-31): # For now, guess that in the future Morocco will fall back at 03:00 # the last Sunday before Ramadan, and spring forward at 02:00 the # first Sunday after two days after Ramadan. To implement this, # transition dates and times for 2019 through 2087 were determined by # running the following program under GNU Emacs 26.3. (This algorithm # also produces the correct transition dates for 2016 through 2018, # though the times differ due to Morocco's time zone change in 2018.) # (let ((islamic-year 1440)) # (require 'cal-islam) # (while (< islamic-year 1511) # (let ((a (calendar-islamic-to-absolute (list 9 1 islamic-year))) # (b (+ 2 (calendar-islamic-to-absolute (list 10 1 islamic-year)))) # (sunday 0)) # (while (/= sunday (mod (setq a (1- a)) 7))) # (while (/= sunday (mod b 7)) # (setq b (1+ b))) # (setq a (calendar-gregorian-from-absolute a)) # (setq b (calendar-gregorian-from-absolute b)) # (insert # (format # (concat "Rule\tMorocco\t%d\tonly\t-\t%s\t%2d\t 3:00\t-1:00\t-\n" # "Rule\tMorocco\t%d\tonly\t-\t%s\t%2d\t 2:00\t0\t-\n") # (car (cdr (cdr a))) (calendar-month-name (car a) t) (car (cdr a)) # (car (cdr (cdr b))) (calendar-month-name (car b) t) (car (cdr b))))) # (setq islamic-year (+ 1 islamic-year))))
  - h2odragon 5y ago
    I was sortof idly wondering the other day if anyone had "done" holiday calendar calculations in an easy library yet, or if emacs was still the best source. This argues emacs calendar is the gold standard implementation.
- gerikson 5y ago
  Morocco isn't that far south, it's on the same latitude as the American South. I missed them being on permanent "summer time" (UTC+1) except Ramadan. Our customers deal with contact centers and they do a lot of business with France, so this is major headache for them.
pantulis 5y ago
And what do they observe? Is some kind of astronomical event?
- deleted 5y ago
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- deleted 5y ago
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- andreareina 5y ago
  New moon[1] > Since the new moon is not in the same state at the same time globally, the beginning and ending dates of Ramadan depend on what lunar sightings are received in each respective location. As a result, Ramadan dates vary in different countries, but usually only by a day. [1] https://en.wikipedia.org/wiki/Ramadan_(calendar_month) https://en.wikipedia.org/wiki/Ramadan_(calendar_month)
- bloak 5y ago
  They observe the crescent moon just after sunset. Although officially the month starts when an official sees the new moon, I wonder to what extent they predict in advance when the moon is likely to be visible and then, in order to avoid unnecessary disruption, they make sure that that is indeed when they see it.
  - shagie 5y ago
    https://www.abc.net.au/science/articles/2005/04/25/1352797.htm?site=galileo/scribblygum&topic=latest https://www.abc.net.au/science/articles/2005/04/25/1352797.h... > The OIC says religious scholars will have access to accurate pictures of the shape of the Moon instead of having to rely on naked-eye sightings which have in the past created discrepancies between Muslim countries or mistakes. > "Hopefully the satellite will stop the problems associated with lunar sightings," spokesman Ahmed Imigene says. > "The satellite will have a fixed camera on board that will take highly detailed pictures of the Moon and beam them back to earth," says Professor Mervat Awad, the centre's director. > Dr Ali Juma, chief of the 15-member panel from Saudi Arabia, Egypt, the United Arab Emirates and Bahrain which decided on the contract for the satellite, says it will solve many problems related to crescent sighting. Though... not all countries use that technology. I'm not sure if its still in use as that was 15 years ago.
FiReaNG3L 5y ago
When two sets of arbitrary non-sense rules collide!
- geoduck14 5y ago
  >When two sets of arbitrary non-sense rules collide! I bet 2 VPs were trying to determine the direction for their teams.

signal11 5y ago

For people wondering why Morocco has DST (which isn’t that useful for countries relatively close to the equator?), it seems Morocco chose to permanently become UTC+1 in 2018, with the exception of Ramadan, when it’s UTC. So it’s not really DST in the summer months as done in Europe. Although the Moroccan approach makes for an interesting technical challenge!

shagie 5y ago
Searching for Ramadan in https://github.com/eggert/tz/blob/main/asia https://github.com/eggert/tz/blob/main/asia and https://github.com/eggert/tz/blob/main/africa https://github.com/eggert/tz/blob/main/africa is an interesting read. Morocco textual history is at https://github.com/eggert/tz/blob/main/africa#L628 https://github.com/eggert/tz/blob/main/africa#L628 and the implementation rules are at https://github.com/eggert/tz/blob/main/africa#L903 https://github.com/eggert/tz/blob/main/africa#L903 Just above that is this bit: # From Paul Eggert (2020-05-31): # For now, guess that in the future Morocco will fall back at 03:00 # the last Sunday before Ramadan, and spring forward at 02:00 the # first Sunday after two days after Ramadan. To implement this, # transition dates and times for 2019 through 2087 were determined by # running the following program under GNU Emacs 26.3. (This algorithm # also produces the correct transition dates for 2016 through 2018, # though the times differ due to Morocco's time zone change in 2018.) # (let ((islamic-year 1440)) # (require 'cal-islam) # (while (< islamic-year 1511) # (let ((a (calendar-islamic-to-absolute (list 9 1 islamic-year))) # (b (+ 2 (calendar-islamic-to-absolute (list 10 1 islamic-year)))) # (sunday 0)) # (while (/= sunday (mod (setq a (1- a)) 7))) # (while (/= sunday (mod b 7)) # (setq b (1+ b))) # (setq a (calendar-gregorian-from-absolute a)) # (setq b (calendar-gregorian-from-absolute b)) # (insert # (format # (concat "Rule\tMorocco\t%d\tonly\t-\t%s\t%2d\t 3:00\t-1:00\t-\n" # "Rule\tMorocco\t%d\tonly\t-\t%s\t%2d\t 2:00\t0\t-\n") # (car (cdr (cdr a))) (calendar-month-name (car a) t) (car (cdr a)) # (car (cdr (cdr b))) (calendar-month-name (car b) t) (car (cdr b))))) # (setq islamic-year (+ 1 islamic-year))))
- h2odragon 5y ago
  I was sortof idly wondering the other day if anyone had "done" holiday calendar calculations in an easy library yet, or if emacs was still the best source. This argues emacs calendar is the gold standard implementation.
gerikson 5y ago
Morocco isn't that far south, it's on the same latitude as the American South. I missed them being on permanent "summer time" (UTC+1) except Ramadan. Our customers deal with contact centers and they do a lot of business with France, so this is major headache for them.

pantulis 5y ago

And what do they observe? Is some kind of astronomical event?

deleted 5y ago
[deleted]
deleted 5y ago
[deleted]
andreareina 5y ago
New moon[1] > Since the new moon is not in the same state at the same time globally, the beginning and ending dates of Ramadan depend on what lunar sightings are received in each respective location. As a result, Ramadan dates vary in different countries, but usually only by a day. [1] https://en.wikipedia.org/wiki/Ramadan_(calendar_month) https://en.wikipedia.org/wiki/Ramadan_(calendar_month)
bloak 5y ago
They observe the crescent moon just after sunset. Although officially the month starts when an official sees the new moon, I wonder to what extent they predict in advance when the moon is likely to be visible and then, in order to avoid unnecessary disruption, they make sure that that is indeed when they see it.
- shagie 5y ago
  https://www.abc.net.au/science/articles/2005/04/25/1352797.htm?site=galileo/scribblygum&topic=latest https://www.abc.net.au/science/articles/2005/04/25/1352797.h... > The OIC says religious scholars will have access to accurate pictures of the shape of the Moon instead of having to rely on naked-eye sightings which have in the past created discrepancies between Muslim countries or mistakes. > "Hopefully the satellite will stop the problems associated with lunar sightings," spokesman Ahmed Imigene says. > "The satellite will have a fixed camera on board that will take highly detailed pictures of the Moon and beam them back to earth," says Professor Mervat Awad, the centre's director. > Dr Ali Juma, chief of the 15-member panel from Saudi Arabia, Egypt, the United Arab Emirates and Bahrain which decided on the contract for the satellite, says it will solve many problems related to crescent sighting. Though... not all countries use that technology. I'm not sure if its still in use as that was 15 years ago.

FiReaNG3L 5y ago

When two sets of arbitrary non-sense rules collide!

geoduck14 5y ago
>When two sets of arbitrary non-sense rules collide! I bet 2 VPs were trying to determine the direction for their teams.