Aperture Synthesis Spectral Line Imaging: Exploring the Third Dimension (Invited Talk)

Radio astronomers are in a privileged position as compared to optical and near-IR observers because almost from the beginning of radioastronomical observations it proved possible to obtain spectral information at velocity resolutions of order of several km s[to minus1]. Currently, single dish telescopes equipped with multi-beam receivers, scanning the sky "on the fly", fitted with powerful digital backends (digital autocorrelators) or aperture synthesis telescopes doted with even more impressive digital crosscorrelators routinely collect stunning sD images across the radio window, from (sub)mm all the way to meter wavelengths. In this talk I will give a summary of some of the characteristics of the world's most powerful radio telescopes, show some examples of state-of-the-art radio observations as applied to studies of the ISM in nearby (dwarf) galaxies, and refer to some of the radio telescopes of the future, such as the LMT, ALMA and the plans for a Square Kilometer Array (SKA).