* Paul Eggert:
On 5/30/20 7:00 AM, Florian Weimer wrote:
Would this be a good opportunity to engage with the government of Morocco to encourage them to give more warning? My understanding is that at present, they don't know themselves in advance.
Yes, I think you're right.
They would have to redefine the criteria to something based exclusively on astronomical calculations
That shouldn't be necessary, as they're using a conservative approximation; that is, it's OK if their approximation is a bit off because all they need to do is to bracket the actual Ramadan rather than predict its Gregorian dates exactly. If they had an algorithm they could publish it and we could use it. And it would be technically feasible for them to have an algorithm; see the Morocco-prediction code in the tzdb 'africa' file for an example algorithm.
It looks like the algorithm predicted correctly the data of Eid al-Fitr as 24 May, but the derivation of the end date from that is suspicious. I think it would make more sense if the time change does not happen on Eid itself. A rule like this would ensure that Eid still uses the same time as Ramadan in every year, which is likely what people expect.