Book excerpt: This substantially rewritten and expanded fourth edition outlines the most up-to-date methods and tools of radio astronomy. Tools of Radio Astronomy gives a unified treatment of the entire field of radio astronomy, from centimeter to sub-millimeter wavelengths and using single telescopes as well as interferometers. The basic physical principles are described and a complete outline of the instrumentation, observational techniques, and methods of measurement and analysis are given. The goal of this standard reference and text is to prepare readers to carry out observations and relate the data to physical processes in interstellar space. In this fourth edition, the chapter on interferometry and aperture synthesis has been thoroughly revised in the light of most recent developments, as has been the chapter on molecules in interstellar space, and material on receiver technology. From reviews of previous editions: "People use this book so much because it describes what one needs in order actually to do radio astronomy ... and it will remain relevant for a long time...This book is an excellent graduate level text - the best available by far. It is also the best reference book for the practising astronomer who wants to do radio astronomy properly, to interpret the jargon or to understand some of the details of current literature." Physics Today "This is the one book you should buy if you want to become a radio astronomer. (...) I have used the first and second editions as a postgraduate textbook for many years, and will now recommend the third edition to my students." The Observatory.