[tz] FW: [Ext] The TZ Coordination

Paul Eggert eggert at cs.ucla.edu
Sat May 30 23:03:54 UTC 2020

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.

Admittedly there are obstacles to getting all this to work. That being said, I
suspect that the obstacles here are administrative, not religious or technical.

We needed a tzdb 2020a because in 2019c I had predicted a tighter bound around
the actual Ramadan, whereas the Moroccan authorities evidently wanted a looser
bound. That is, Ramadan ended May 23 in Morocco, and tzdb 2019c had predicted
May 24 for the spring-forward transition whereas the Moroccan government decided
on May 31.

PS. In about three hours the discrepancy will become moot, as Morocco will do
its end-of-Ramadan spring-forward and after that the 2019c clocks will agree
with the 2020a clocks.

More information about the tz mailing list