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arcseconds

Arcseconds are units of angular measurement equal to 1/3600 of a degree. Since there are 2π radians in a circle, one arcsecond equals about 4.8481 × 10^-6 radians, and there are about 206,265 arcseconds per radian.

In astronomy, arcseconds are used to express small angles such as the apparent separations of stars, the

The parallax method defines the parsec: one parsec is the distance at which 1 AU subtends an

Subunits include milliarcseconds and microarcseconds. They enable precise astrometry with missions such as Gaia and techniques

The angular resolution of a telescope is often described by the diffraction limit, θ ≈ 1.22 λ / D radians,

apparent
diameters
of
planets,
and
the
resolutions
of
telescopes.
The
Sun's
and
Moon's
apparent
diameters
are
on
the
order
of
1,900
and
1,800
arcseconds,
respectively.
angle
of
one
arcsecond.
This
corresponds
to
about
3.26
light-years
or
3.086
×
10^16
meters.
like
very
long
baseline
interferometry,
which
can
reach
microarcsecond
accuracy.
which
translates
to
approximately
206,265
×
(1.22
λ
/
D)
arcseconds.
This
connects
the
physical
size
of
an
aperture
and
the
observing
wavelength
to
the
smallest
angular
detail
that
can
be
resolved.