Question on how to add Mount Athos to timezones

Paul Eggert eggert at CS.UCLA.EDU
Fri Apr 20 23:27:32 UTC 2007

"Olson, Arthur David \(NIH/NCI\) [E]" <olsona at> writes:

> A monk from Greece would like to
> set their Suse Linux Systems to Athonite Time, which is basically 13
> days behind the rest of the world.

As I understand it, Athonite time (sometimes also called "Byzantine
time") not only uses the Julian calendar, but each day begins at
sunset.  So, for example, morning vespers are at
08:00 Athonite time, which is roughly (but not exactly) 02:00 local
mean time.  Since the clock starts at sunset, the difference between
Athonite time and ordinary time is not a fixed offset: it varies
during the year.

I wouldn't be surprised if the inhabitants of Mt. Athos would prefer
to use the ancient Greek and Roman unequal hours, where the length of
the hour depends on the length of that particular night and day.  The
ancients didn't need to worry about DST, since their clocks ran slower
during summer days (and faster in summer nights) so that there were
always exactly 12 hours from every sunrise to sunset and vice versa.
Pretty cool, huh?

Anyway, regardless of whether Mt. Athos prefers unequal or equal
hours, I'm afraid it's not the sort of thing that you can implement by
adding a few lines of code of your C library, unless your definition
of "few" is a lot larger than mine....

I'll CC: this message to your correspondent, who can double-check my
research if he has the time.  I'm particularly interested in finding
out whether Mt. Athos actually uses unequal hours.

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