We have used the Nordic Optical and the William Herschel Telescopes to obtain images and long-slit spectra of Cygnus A under conditions of sub-arcsecond seeing. The high spatial resolution and accurate positional information obtained from a comparison between the images and spectra allow us to study in detail the kinematics and excitation of the

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The scientific objective of the VIRGO experiment (Variability of solar IRradiance and Gravity Oscillations) is to determine the characteristics of pressure and internal gravity oscillations by observing irradiance and radiance variations, to measure the solar total and spectral irradiance and to quantify their variability over periods of days to

A ring-diagram analysis of solar oscillations has been applied to a 3 day time series of full-disk Doppler images obtained at Mount Wilson. A model of the three-dimensional power spectrum assuming a Lorentzian profile in frequency and the advection of the wave front by horizontal flows has been fitted to the observed spectrum. The model provides