The ADS maintains three bibliographic databases containing more than 14.2 million records covering publications in Astronomy and Astrophysics, Physics, and the arXiv e-prints.
NED is a comprehensive database of multiwavelength data for extragalactic objects, from hundreds of large sky surveys and tens of thousands of research publications, spanning the entire observed spectrum from gamma rays through radio frequencies.
The Sloan Digital Sky Survey has created the most detailed three-dimensional maps of the Universe ever made, with deep multi-color images of one third of the sky, and spectra for more than three million astronomical objects.
Publisher: Strasbourg astronomical Data Center (CDS)
Information on astronomical objects of interest which have been studied in scientific articles, including a bibliography, and other available basic information such as the nature of the object, its coordinates, magnitudes, proper motions and parallax, velocity/redshift, size, spectral or morphological type, and the multitude of names (identifiers) given in the literature.