A
minute of arc (
MOA),
arcminute (
arcmin) or
minute arc is a unit of
angular measurement equal to one-sixtieth of one
degree. As one degree is of a circle, one minute of arc is of a circle (or, in
radians, ). It is used in fields that involve very small angles, such as
astronomy,
optometry,
ophthalmology,
optics,
navigation,
land surveying and
marksmanship.