3.2. NASA/IPAC Extragalactic Database (NED)
NED (/; telnet ned.ipac.caltech.edu username: ned) contains information about 800,000 extragalactic objects which includes 1.3M names and almost a million bibliographic references (since 1983), abstracts (since 1988) and notes on the sources. NED is the place to start on a project that includes extragalactic sources and is freely available to anyone with Internet access.
NED includes an object-based database, it organizes all information around individual extragalactic objects not by catalogs (Helou et al 1995). The master list was culled from around 40 major astronomical catalogs plus several lists from the literature (for example PG quasars or compact groups of galaxies). NED team members continuously produce the cross identification of each source in the list.
The information for each of the sources (if available) includes:
Each entry includes the reference where the information was published.
NED also includes abstracts of dissertations devoted to extragalactic studies presented since 1980. Dissertation titles and authors only are available for theses presented between 1909 and 1980.
It is very easy to search for information in NED as you do not need to know much about the object. The query can be made by name, near a position (in equatorial, ecliptic, galactic or super-galactic), IAU formatted name for an object near a position or by object type. The list can also be created also in such a way that object types are excluded from those retrieved inside a searching radius.
If the list is long, a batch job request can be submitted. The user will send an e-mail message to email@example.com and NED will reply with the desired information in one or more messages. NED can also be run in a client mode, making it possible to access the database from within user programs.
To complete the search an image of the object (or the region) can be obtained. NED can produce images from the Digitized Sky Survey, infrared images from the IRAS survey and radio maps.