Charles Messier's catalog of nebulae and star clusters, published in 1784, marked the start of a new era of deep-sky astronomy. Today, this tradition of observing galaxies and clusters is kept alive by dedicated amateur astronomers. Nearly all the objects are visible in a small telescope, and many, such as the Crab Nebula and the Andromeda galaxy, are among the most fascinating objects in the universe. Kenneth Glyn Jones has revised his definitive version of Messier's catalog. His own observations and drawings, together with maps and diagrams, make this a valuable introduction to deep-sky observing. Historical and astrophysical notes bring the science of these nebulae right up to date. This is a unique handbook, unlikely ever to be equaled in its completeness and importance to the telescope owner.