[tz] Calculating dates of Ramadan

Tim Thornton tt at smartcomsoftware.com
Wed May 16 09:28:11 UTC 2012

Regarding calculating Ramadan:
The Islamic calendar is lunar, not solar, and is about 11 or 12 days shorter
than the "normal" Gregorian calendar.
Months (including Ramadan) start when the first crescent of a new moon is
sighted. This varies according to the atmospheric conditions and the exact
positions of earth, sun and moon, but can be calculated to within about a
day for any given location, which is good enough for tz data in the absence
of any further specific information for a location.
There is also an ongoing debate in Islam on whether the calculated date is
good enough, or whether they should stick with past practice of having
official observers watching the sky to announce the start of the month.
What cannot be done is to say that it always falls between a given pair of
Gregorian calendar dates, due to its shifting.


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-----Original Message-----
From: tz-bounces at iana.org [mailto:tz-bounces at iana.org] On Behalf Of Ian
Sent: 16 May 2012 09:59
To: tz at iana.org
Subject: Re: [tz] Morocco Daylight Saving Time

On 2012-05-16 09:26, Mohamed Essedik Najd wrote:
> Good Morning Everyone;
> I am  really glad that I have joined this mailing list.
> I just wanted to tell you that Morocco passed to DST during the last 
> week end of April and this will remain active till the last weekend of 
> September ,  with a suspension during Ramadan (Roughly between 20 
> July,
> 19 august, [Lunar Month, not sure yet])

I know establishing the start of Ramadan isn't an exact science, but surely
there are lower and upper bounds that law-makers could use for DST purposes?

-=( Ian Abbott @ MEV Ltd.    E-mail: <abbotti at mev.co.uk>        )=-
-=( Tel: +44 (0)161 477 1898   FAX: +44 (0)161 718 3587         )=-

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