On 2024-02-03 13:06, brian.inglis--- via tz wrote:
There should be some better sources available of accurate astronomical moon sighting calculations
The timestamps TZDB documents are civil timestamps, not religious ones. This is why TZDB cites the Palestinian Cabinet's predictions, not the astronomical observations that are the basis of the Islamic calendar. Although I don't know, I guess that start-of-Ramadan crescent moon sightings in Palestine are evaluated by an investigation committee of the Palestinian Fatwa House <https://www.darifta.ps/>. If so, surely the Cabinet would defer to the Fatwa House if the Cabinet's conservative predictions of a period of time around Ramadan turn out to be not conservative enough. However, if this (dare I say it?) astronomically improbable event occurs, that won't change the start and end of Ramadan - all it would mean is that legal clock changes wouldn't match Ramadan that year, due to the Cabinet's mistake. At most the Cabinet would make some last-second correction (perhaps even an ex-post-facto correction!) and tzdata could continue to cite just the Cabinet. This is because TZDB's goal is to document what human clocks say, not what the earth and moon are doing.