A gold openface perpetual calendar watch with moon phases, Audemars Piguet, no. 146, circa 1980,

18k, nickel lever movement, adjusted to heat, cold, isochronism and 5 positions, monometallic compensation balance, 20 jewels, silvered matte dial, four subsidiary dials indicating day, date, months calibrated for leap year and ages combined with phases of the moon, case with stepped bezel, snap back, case, dial and movement signed, with tie tag.