10 - The New General Catalogue: publication, analysis and effects

Summary

After having presented all of the information which contributed to the making of the NGC, this section treats Dreyer's publication of 1888 and analyses the structure of the catalogue. It appeared in Vol. 49 of the Memoirs of the Royal Astronomical Society and is titled ‘A new catalogue of nebulae and of clusters of stars, being the catalogue of the late Sir John F. W. Herschel, Bart., revised, corrected, and enlarged’ (Dreyer 1888b). The main topics of the following Sections 10.1 and 10.2 are:

• the temporal development of discoveries (1800–1887)

• the number of independent NGC objects

• discoverers (success rate, nationality)

• telescopes (aperture, type, site, nationality)

• the distribution according to modern object types

• the presentation of special objects

• the distribution of visual brightness

• missing data

After 1888, Dreyer and other astronomers collected corrections and supplementary data regarding NGC objects. Moreover, many new non-stellar objects were found, mainly by photography. To keep track, Dreyer published two Index Catalogues, in 1895 and 1908, containing the new data (Section 10.3). NGC-numbers are mentioned in nearly all modern catalogues (e.g. of galaxies, galactic nebulae and open clusters), albeit not always correctly. This is mainly due to the fact that the original NGC is not user-friendly and thus difficult to compare with modern data. Moreover, it contains errors, which were simply reproduced.