The NASA/IPAC Extragalactic Database (NED) 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 flexible retrieval
of the information via the Internet.
It is accessible anonymously and free
of charge to any account on the networks, and used primarily by
researchers, students and librarians. NED is physically located at the
Infrared Processing and Analysis Center (IPAC) on the Caltech campus.
NED provides an object-based representation of the extragalactic sky, with
accurately located sources and coherently presented data, and direct links
from this information to the refereed literature. NED 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 literature.
The resulting database is augmented with a systematic bibliography, with
well-characterized measurements for each object, and with notes from
catalogs and the literature. NED can be searched for objects in a variety
of ways, including constraints on positions, redshifts and type of object,
and will 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 papers published since 1988, and of theses from
English-language institutions.
The printed chapter addresses the following items: