THE NEW GENERAL CATALOGUE
In 1874, the largest telescope in the world was owned by an amateur astronomer. At his ancestral home of Bin Castle, Ireland, the third Earl of Rosse, William Parsons, built what became known as the "Leviathan of Parsonstown". For its day, it was a monster—a 72 inch (1.8 m) diameter telescope slung on cables between two massive brick walls.
With this unwieldy instrument, Rosse discovered that many "nebulas" had a spiral shape. Today we know them to be spiral galaxies. Rosse himself rarely used the telescope, but many other keen observers did. Among them was Johann Louis Emil Dreyer. Dreyer served as Rosse's assistant from
1874 to 1878, recording the mysterious spiral nebulas, among others, with sketch pad and notebook.
By 1886, Dreyer and other observers had discovered so many nebulas and star clusters that a new catalog was needed. The
Royal Astronomical Society assigned Dreyer the task. Published in 1888, the New General Catalogue (NGC) contained entries for 7,840 objects: The two Index Catalogues (IC) later added another
5,386 objects, some discovered with the newly invented process of photography. A century later, the 13,000-plus objects of the NGC and IC lists form the core of all of
today's comprehensive databases of deep-sky wonders.