Different countries calculate a 'secular' start of Islamic month differently than others. I am aware for example that the astronomical rules used to calculate this 'secular' stat of month are different in Egypt, than in Saudi Arabia or Pakistan. But the Imams have the right to declare the religious start of month whenever they deem fit, which in the case of some countries could be before the their 'secular' calculation. On 2012-05-16 6:29, Ian Abbott wrote:
On 2012-05-16 10:28, Tim Thornton wrote:
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.
Tim
In practice, how much does the observed (as in astronomical) date differ from the calculated date? Does it ever start _before_ the calculated date?
--