NGC 604, one of the largest and brightest known emission nebulae in the universe, is readily visible in backyard telescopes, and is fairly well-known in the amateur community. But did you know that the New General Catalogue lists three other nebulae within M33? The Index Catalog (IC) lists ten more concentrations, and hundreds have been cataloged.
In 2002 and 2003, well-known Canadian stargazer Alan Whitman identified seven distinct nebulae and star clouds within M33 using his 8-inch scope, and more than 30 using his 16-incher. He wrote up his observations, complete with an illustrated guide, for the December 2004 issue of Sky & Telescope. Click here to download a 300-Kb PDF of the article.