Describes the blurring of a stellar (point-like) image due to turbulence in the Earth's atmosphere, both at high altitudes and within the telescope dome Seeing estimates are often given in terms of the frill-width in arcseconds of the image at the points where the intensity has fallen to half its peak value The typical value at a good site is a little better than 1 arcsecond
The steadiness of the Earth's atmosphere, which sets limits on the detail with which objects can be studied with ground-based telescopes Good seeing corresponds to a spread in a point source of radiation to less than one arcsecond
A term used to describe the ease with which good telescopic observations can be made from Earth's surface, given the blurring effects of atmospheric turbulence
The movement or distortion of a telescopic image as a result of turbulence in the Earths atmosphere
a measure of the amount of turbulence of the air When the seeing is ``good'', the amount of turbulence is small and the images are steady (little twinkling) ``Poor'' seeing occurs when the atmosphere is turbulent so the images shimmer and dance around (more twinkling)