10 The NASA / IPAC Extragalactic Database

The NASA/IPAC Extragalactic I~atabase (INED) is an electronic research tool which provides uniquely powerful access to published multi-wavelength data on extragalactic objects. It consists of a computer database with a broad range of published information, and a user interface which allows fast and flexiblc~ retrieval of the information via the lntm-net. It is accessible anonymously and free of charge to any account cm the networks, and used primarily by researchers, students and librarians. NED is physically located at the Infrared Processing and Analysis Center (11’AC) cm thdCaltech campus ~),,:.:,. [lf(( [(, ( ~ (’k (<’<J ‘, ,, ,“4. ~ . in Pasadena, California (lJSA). ..’ll/: ,,{,/ ,!’~: 1 /’ NIH~ provides an object-based representation of the extragalaclic sky, with accurately located sources and cohcr~mtly presented data, and direct ]inks from this information to the refereed literature. NIH 1 is built around astronomical sources. Its starting point is a detailed merger of extragalactic catalogs, rather than a collection of juxtaposed catalogs. This merger is constantly enriched by new identifications and by the addition of objects appearing in short lists throughout the litt)rature. The resulting database is augmented with a systematic bibliography, with well-characterized measurements for each object, and with notes from catalo~:s and the literature. N]lD can be searched for objects in a variety of ways, including constraints on positions, redshi fts and type of object, and w i 11 plot the distribution on the sky of objects retrieved. NED can be searched for references by citation or by author name, and will display abstracts of paprs published since 1988, and of theses from English-1 anguage institutions.