Published online by Cambridge University Press: 12 April 2016
Since a lot of efforts and money are being put in building larger telescopes, astronomers are becoming more concern with the effects of “atmospheric seeing” on astronomical observations. Observers need to correct their observations for image degradation and put more and more emphasis on the importance of good seeing conditions. Both observers and optical engineers try to compare the image quality between different telescopes and sites. In addition, engineers are interested in locating the origin of image degradation. What are the relative contributions of the dome and of the free atmosphere to image degradation ? As engineers become able to reduce dome seeing, the selection of a good astronomical site becomes more crucial and reliable methods for site testing become necessary.