Patek Philippe Annual Calendar

Patek Philippe patented the annual calendar in 1996 and introduced it in the reference 5035, a self-winding watch that reads the long and short months by itself and needs one correction a year, at the end of February. It sits between a simple date and a perpetual calendar, since it knows which months run to 30 and 31 days but not February. The tell is three apertures for day, date and month set along the arc of a circle below 12, with a moon phase and 24 hour indication at 6 on many references. Patek files the family under Complications, and it runs from plain round gold references through the regulator, travel time and flyback chronograph versions to diamond set ladies models.