μas
microarcsecond
Angleexact by definition
The microarcsecond is a millionth of an arcsecond, about 4.848 × 10⁻¹² radians. It is the frontier of angular measurement: the Event Horizon Telescope resolved structure at roughly 20 μas, and Gaia's best parallaxes for bright stars reach a few tens of μas.
| 1 μas | 2.7777778e-10 ° |
Where the unit came from
To make the size concrete, a microarcsecond is roughly the angle subtended by a full stop on the Moon as seen from Earth. Reaching it requires either an interferometer the width of the planet or a spacecraft scanning the sky for years.
Solvers that use angle