Perpetual Calendar - Patek Philippe 5372 Mode D'emploi

PERPETUAL CALENDAR

The perpetual calendar indicates the date, the day
of the week, and the month, automatically taking
into account months with 28, 29, 30, and 31 days: it
switches directly from September 30 to October 1 or,
in non-leap years, from February 28 to March 1. The
date, day, and month are complemented by a leap-
year indication and a moon-phase display, which is
so accurate that it deviates from the true lunar cycle
by only one day every 122 years. If the watch is wound
daily, the perpetual calendar will not require any
corrections before February 28, 2100; this is a secular
year that by exception omits the 29th of February.
Note: The date change mechanism is active between 10 pm and
2 am whereas the moon phase switches between 12 noon and 2
pm. During these time periods, adjustments of the calendar and
moon-phase indications with the correction push pieces should
be avoided. To assure that corrections will not interfere with the
operation of these mechanisms, first set your watch to 6 am;
observe the day/night indicator (white range). If your watch
has stopped running, do not make corrections or adjustments
before rewinding it with about 15 clockwise turns of the crown.
Correction push pieces should be actuated exclusively with the
correction stylus that was delivered with the watch. The use of
any other tool could damage your timepiece. The adjustments
must be performed in the order described below.
DATE CORRECTION
To set the date, actuate the correction push piece at 12
o'clock as many times as needed to display the current
date. The day of the week will advance simultaneously
with the date, but it can also be corrected separately if
it does not correspond to the date. The moon phase
can also be corrected separately.
CORRECTION OF LEAP-YEAR CYCLE AND MONTH
To simultaneously set these two displays, press the
correction push piece between 12 and 1 o'clock
as often as needed to display the desired year
numeral (4 = leap year, 1 = 1st year after a leap year,
2 = 2nd year after a leap year, 3 = 3rd year after a
leap year) and the correct month are displayed.
For guidance on the leap-year cycle, consult the
brochure entitled "Leap year and full moon calendar".