Sky Surveys and Virtual Observatories

Astronomers have always catalogued the objects they observe and study. In ancient times, the Greek astronomer Hipparchos (between 161 and 127 BC) and the Chinese astronomers Shi Shen and Gan De (in the Warring States period, around 500 BC) built up the first systematic catalogues of the celestial regions accessible from their parts of the world. Tycho Brahe did likewise, followed by surveys of non-stellar objects, such as Messier’s.1 At the end of the nineteenth century, sky surveys marked the beginning of the great modern catalogues. Computers completely transformed this landscape in the last decade of the twentieth century, by vastly increasing the volumes of data that could be stored, while improving accessibility, addressability, and communications through a range of automated systems. In this chapter, we shall consider some of the results of this revolution. In addition to the development of statistical astrophysics and systematic whole sky surveys across all wavelengths, we will also discuss the advent of virtual observatories which bring together all available maps and data about a specific object, to assist in solving whatever astrophysical problem is under investigation.