[tz] Eternal DST rules for Morocco from 2012 at last

[OvV_HN]

From:
Dan Abitbol dabitbol at streamwide.com
Thu Mar 15 10:21:07 UTC 2012

Hello

Sorry to disturb again but as you know Morocco have new DST rules and first 
change is scheduled on 25 March 15, 2012-03-15
Do you plan to release 2012c that takes into account these new rules for 
Morocco soon ?
..............


Reply:

This is not going to be easy.
If I understand the rules correctly, then the clocks will be put back during 
the month of Ramadan.
Since the Islamic calendar wanders through the Gregorian calendar, in some 
years the full month of Ramadan falls in the summertime period, in some 
years Ramadan falls in the wintertime period and in other years the month of 
Ramadan partially overlaps with the DST period.
I made a table for a couple of forthcoming years.

Please note that this table is useless!
The beginning of an Islamic month starts as soon as a religious authority 
declares that the crescent of the moon, immediately after an astronomical 
new moon, has been observed.
This can't be predicted, but it can be approximated by some algorithm. For 
the table I have used the algorithm for the arithmetical Islamic calendar 
from Reingold in Calendrical Calculations 2.
Note that an Islamic day actually starts at sunset of the day before the day 
mentioned.

Table. (Best viewed with a monospace font).

Column 1: Islamic year count.
Column 2: the last Sunday of March in the Gregorian calendar.
Column 3: the last Sunday of September in the Gregorian calendar.
Column 4: the first day of the islamic month Ramadan in the Gregorian 
calendar.
Column 5: the last day of the islamic month Ramadan in the Gregorian 
calendar.

Islamic last Sun. last Sun. first of    last of
year    March     Sept.     Ramadan     Ramadan
                            Gregorian   Gregorian
1433  2012-3-25  2012-9-30  2012-7-20   2012-8-18
1434  2013-3-31  2013-9-29  2013-7-9    2013-8-7
1435  2014-3-30  2014-9-28  2014-6-29   2014-7-28
1436  2015-3-29  2015-9-27  2015-6-18   2015-7-17
1437  2016-3-27  2016-9-25  2016-6-7    2016-7-6
1438  2017-3-26  2017-9-24  2017-5-27   2017-6-25
1439  2018-3-25  2018-9-30  2018-5-16   2018-6-14
1440  2019-3-31  2019-9-29  2019-5-6    2019-6-4
1441  2020-3-29  2020-9-27  2020-4-24   2020-5-23
1442  2021-3-28  2021-9-26  2021-4-13   2021-5-12
1443  2022-3-27  2022-9-25  2022-4-3    2022-5-2
1444  2023-3-26  2023-9-24  2023-3-23   2023-4-21
1445  2024-3-31  2024-9-29  2024-3-11   2024-4-9
1446  2025-3-30  2025-9-28  2025-3-1    2025-3-30
1447  2026-3-29  2026-9-27  2026-2-18   2026-3-19
1448  2027-3-28  2027-9-26  2027-2-8    2027-3-9
1449  2028-3-26  2028-9-24  2028-1-28   2028-2-26
1450  2029-3-25  2029-9-30  2029-1-16   2029-2-14
1451  2030-3-31  2030-9-29  2030-1-6    2030-2-4
1452  2031-3-30  2031-9-28  2030-12-26  2031-1-24
1453  2032-3-28  2032-9-26  2031-12-15  2032-1-13

>From the table you can see that, for instance, in the Gregorian year 2012 
the month Ramadan completely falls in the summertime period.
In the Gregorian year 2026 the full month Ramadan falls outside the 
summertime period.
In the Gregorian year 2023 Moroccan summertime starts effectively April 21 
plus one (this is 1 Shawwal) (give or take 2 days; see above why), since 
Ramadan started just before the last Sunday of March.
That's my interpretation, which can differ from the official one!


Oscar van Vlijmen