ABSTRACT
This chapter is devoted to ground-based optical observations, instrumentation and analysis techniques that are generally used in solar physics. Ground-based solar optical observations require careful site surveys over extended periods to select suitable sites with good atmospheric seeing, low dust and water vapour content, and large number of cloud-free days in a year. Various types of telescope configurations along with the specific requirements for solar observing, dome designs, mounts, and backend instruments aided with active and adaptive optics capabilities, are discussed. The need to optimise diffraction-limited resolutions with the atmospheric seeing of the site is elaborated. High altitude sites, surrounded by large bodies of water, appear to provide better quality of observations. Solar imaging and analysis techniques using interference and birefringent filters, spectroscopic methods, and solar spectrographs are described. These techniques are employed to observe not just the photosphere, but also the usually invisible, fainter layers of outer solar atmosphere by blocking the bright light of photosphere by optical filters. The technique of artificial occultations of solar disk is discussed for near-coronal observations in visible coronal emission lines from high altitude sites having very low dust content.
