A
min1ute of arc,
arcminute, or
MOA is a unit of
angular measurement, equal to one sixtieth (1/60) of one
degree. Since one degree is defined as one three hundred sixtieth (1/360) of a circle, 1 MOA is 1/21600 of the amount of arc in a closed circle, or (π/10800)
radians. It is used in those fields which require a unit for the expression of very small amounts of arc, such as
astronomy. The
SI symbol for marking the arcminute is the
prime (′) (
U+2032
,
′
), though a single quote (') (U+0027) is commonly used where only
ASCII characters are permitted. One arcminute is written 1′ (or 1
'). It is also abbreviated as
arcmin or
amin or, less commonly, the prime with a
circumflex over it (
).
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