Omega SA 2520 Watch User Manual

Perpetual calendar
CALIBRE 1680 (fig. V)
The particularity of the Gregorian calendar is that one
day (29th February) is added to the year every four years
to compensate for the length of the solar year, which is
365.242192 days, or almost 365 1/4 days. Such years are
called leap years and their number (e.g. 1996) is divis-
ible by 4.
As the compensation of one day every four years is too
much, every 100 years (2100, 2200, …) the year is not a
leap year, even though it is divisible by four. However, even
this is not totally sufficient, since it leaves an error of one
day every 400 years. Therefore, if the number of the year is
divisible by 400 it is a leap year, as was the case with the
year 2000. Because of this, the perpetual calendar of your
watch is set to function correctly until 2100.
This movement is 10 times more precise than a conven-
tional quartz movement thanks to an electronic module
that compensates for the effects of temperature on the
movement’s operation.
The crown has 3 positions:
Watch functions:
1.1. Neutral position 1, normal when the watch is worn:
in this position, the crown ensures that the watch is
1.2. Setting the hands: minutes and seconds.
Pull the crown out to position 3 when the second
hand is at 12 o’clock. The seconds hand will stop.
Turn the crown forwards or backwards to set the
minute hand.
Push the crown back into position 1 to coincide with
a given time.
NOTE: To avoid inadvertently changing the date when
setting the time, it is important to always follow point
1.2 and then point 1.3.