New General Catalog 1908

The New General Catalogue of Nebulae and Clusters of Stars (NGC), compiled by John Louis Emil Dreyer in 1888, serves as a foundational catalog in astronomy. Over the years, astronomers have engaged in a continual process of revising and updating the NGC to address limitations, correct errors, and incorporate new observations.

Extensions

The NGC, organized by right ascension and featuring unique catalog numbers for various celestial objects, laid the groundwork for subsequent catalogs and supplements. Dreyer himself continued his work with the creation of two Index Catalogues (IC I and IC II) to extend the NGC, incorporating additional objects discovered after the NGC's publication.

Revisions

Revisions to the NGC involve correcting misidentifications, addressing errors resulting from the observational technology of the late 19th century, and separating double entries or recognizing mergers in multi-object systems. Improved positional data, driven by advancements in astrometry, contribute to more accurate location information for NGC objects.

Modern Version

Digital technologies and image processing techniques have played a significant role in the reinterpretation of original observational plates, while observations from modern telescopes, such as the Hubble Space Telescope and surveys like the Sloan Digital Sky Survey (SDSS), contribute high-resolution images and detailed data for NGC objects. Collaborative efforts among astronomers and research institutions ensure that revisions and updates to the NGC reflect the latest advancements and collectively contribute to a more comprehensive and accurate understanding of the universe.