mas
milliarcsecond
Angleexact by definition
The milliarcsecond is a thousandth of an arcsecond, about 4.848 × 10⁻⁹ radians. It is the working unit of modern astrometry: a parallax of 1 mas corresponds to a distance of one kiloparsec, and the Gaia mission measures positions and parallaxes at this level for over a billion stars.
Watch out: Very long baseline interferometry and Gaia both produce angles this small, but they are measuring different things. A parallax in mas inverts to a distance; a proper motion in mas per year is a transverse velocity that also needs the distance before it means anything in kilometres per second.
| 1 mas | 2.7777778e-07 ° |
Solvers that use angle