The isoplanatic angle (θ 0) is the angle for which the variance of the differences of the phase aberrations suffered by two rays of light passing closely through the atmosphere from different points

El brillo de cielo es la medida habitual de cuánto brilla el cielo nocturno en una noche clara sin luna. Es una medida de la calidad del cielo.

Atmospheric extinction evaluates the transparency of the sky. It can be defined as the amount of light from an astronomical object that is scattered or absorbed by the Earth's atmosphere and not

Condiciones meteorlógicas en los Observatorios de Canarias.

Astronomical seeing (units arcesec) refers to the blurring or instantaneous image broadening of astronomical objects caused by turbulent mixing in the Earth's atmosphere due to the variations of the

The coherence time (τ 0) is the time lapse that the light crossing the Earth atmosphere maintains a near-constant phase relationship, both temporally and spatially.