The catalogue was compiled in the 1880s by J. L. E. Dreyer using observations mostly from William Herschel and his son John, and then subsequently expanded with two Index Catalogues (IC I & IC II), adding 5,326 objects.
The catalogue was compiled in the 1880s by J. L. E. Dreyer using observations mostly from William Herschel and his son John, for total of 7,840 objects. The NGC was later expanded with two Index Catalogues (IC I in 1896 & IC II in 1905), adding a further 5,326 objects.