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Issues in Science and Technology Librarianship
Winter 2004

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Database Reviews and Reports

The NASA Astrophysics Data System

Leith B. Woodall
Liaison Librarian, School of Physical Sciences
The University of Queensland Library

General Description

The NASA Astrophysics Data System (ADS) is a digital library for researchers in astronomy and astrophysics. It also covers other subject areas, such as electrical engineering, geophysics, physics, and instrumentation, as they are all loosely related to astronomy and astrophysics. This data system is a NASA funded project and access to all ADS services is free to everybody, through the Internet.

The value of the ADS to astronomical and astrophysical research has been widely recognised, both within the astronomical field, and by libraries. In 2001 Guenther Eichhorn, Project Scientist for ADS, received the Physics, Astronomy and Mathematics Division Award from the Special Libraries Association, and the 2001 van Biesbroeck Prize of the American Astronomical Society was awarded to Michael Kurtz, Scientist with the Harvard-Smithsonian Center for Astrophysics (ADS Awards and Recognition).

The digital library contains over 3.3 million records, which are stored in four databases:

The ADS is considerably smaller than Inspec (over 7 million), which is a major database for physics, electrical engineering and computer science. The value of the ADS is as a specialist database. It combines both astronomical literature and provides access to technical data in the field. The data in the ADS come from a wide range of resources including references and abstracts of articles from all the major journals, many minor journals, monographs, conference proceedings, observatory reports and newsletters, many NASA reports, technical information and PhD theses in the relevant fields. When compared to ISI's Journal Citation Reports, the ADS has a comprehensive coverage of the core journals for astrophysics and astronomy. For physics, approximately 80% of the journals listed by ISI Journal Citation Reports are covered by ADS. In addition to these core journals, many more journals are included.

The initial data set for the ADS came from NASA's Scientific and Technical Information section, and covered the period 1975 - 1995. Subsequently, the data were collected from journals as agreements were reached with individual journals. Additional references are also collected from SIMBAD (Set of Identifications, Measurements and Bibliographies for Astronomical Data), NED (NASA/IPAC Extragalactic Database), conference editors, and individual authors. The ADS is tightly connected with the major journals in astronomy and the major astronomy data centres. In order to provide complete bibliographic coverage, electronic records have been created from table of contents of most journals and conference series back to the first volume. Data is continuously added to the databases, and the web site is updated weekly.

To improve access for all users, the digital library is available on 12 mirror sites around the world, including sites in the USA, South America (Argentina, Brazil and Chile), Europe (France, Germany, Great Britain and Russia), and Asia (China, India, Korea, and Japan).

The ADS is well used by researchers in astronomy and astrophysics. From the table below, it can be seen that this database is increasingly heavily used.

Table of Usage of the NASA Astrophysical Data System
Date No. of users No. of queries No. of references retrieved No. of articles read
March 19991 20,000 580,000 10,000,000 110,000
March 20012 50,000 800,000 28,000,000 130,000
May 20023 60,000 1,000,000 40,000,000 300,000
Sources of information: 1 Kurtz et al. 2000
2 Eichhorn et al. 2002b
3 Eichhorn et al. 2002a

The Data

Many of the papers in the data system are available electronically, either as scanned images, or links to publishers' sites of electronic journals. Users may need to subscribe or obtain usernames and passwords to access these electronic journal articles, but this information is given through the "Access Control Help" link at the top of the page of references found.

There has been a policy of obtaining permission to scan early articles. Permission to do this has been obtained from 40 journals, and for most of these journals scanned articles are available back to the first volume. There are also many observatory reports available in the scanned journals. Many of the scanned images of older journals and observatory reports date to the 1800s.

Searching the Data System

The information can be accessed either by searching references or by browsing the library. Within these options there is some ability to set your own preferences. This is done using cookies. When next you return to that mirror site of the ADS, you will be shown the search interface as you requested. The information on your preferences only applies to the site on which you set it up.

Help is available through a Help button on each screen. There is also help in context on many of the search screens.


Searching References

It is possible to search each of the four databases separately or in any combination. The search interface is a form, which allows the user to combine several query fields. Data collected from SIMBAD, NED, LPI (Lunar and Planetary Institute), and {IAU} (International Astronomical Union) are only searchable in the Astronomy and Astrophysics database.

[Search screen]

Author Searching

There are some useful features in author searching. When searching for an author, the last name and first initial are sufficient to find papers by the author. There is an author synonym list that allows for different spelling of the same author's names to be retrieved automatically. This feature will also capture different forms of a name e.g. when the full names or initials are used. It is also possible to limit author searching to find papers in which the author is the first author, the last author or by combining these limits, find papers in which the author is the sole author.

^drinkwater, j will find papers with J Drinkwater as the first author
drinkwater, j$ will find papers with J Drinkwater as the last author
^ drinkwater, j$ will find papers with J Drinkwater as the only author.

Title Words or Abstract Words Searching

When two or more words are typed into the search box, the radio button you have checked determines the way they are searched.

Two forms of logic are available. Simple Logic allows the use of "+" or "-" in front of a word to indicate its inclusion or exclusion. Many users would be familiar with this form of searching because it is used by search engines such as Google. Boolean logic is also available and can be used for more complex searches.

Two truncation characters are used in the database. The "*" replaces zero or more characters, and the "?", which can be used within a word, replaces single characters. The "*" cannot be used within a word, but it can be used at the beginning or end of a word e.g. *sorb will find absorb or adsorb.

It is possible to limit your search in a number of ways.

On the search screen there is a link to "Journal/Volume/Page" "Current Journals" or "Unread Journals". The "Current Journals" takes you to the current issue of selected journals, and the "Unread Journals" takes you to those current journals you have not read. You can select which journals you want to read through the "Preferences Settings Form". Cookies are used to monitor your preferences and ensure that you only see those journals when next you visit the site.

Browse Library

There are a number of options to browse the database.

[Browse screen]

The journal/Volume/Page service allows you to search individual journals. If you want to know which journals are available, you can follow the link and then select from all journals (includes Observatory bulletins and circulars), all conferences (includes NASA reports and books), refereed journals or non-refereed journals.

The scanned article service gives the choice of:

Other Features

Translation of abstracts
While all the abstracts I have viewed have been in English, the developers of the ADS have recognized that this is an international research tool, and not all the users will have English as a first language. When an abstract is retrieved, there is an option to translate the abstract using Alta Vista's Babel Fish Translation.
Saving search results
Search results can be saved in a number of formats, including HTML, Dublin core XML, EndNote or Procite. This makes the data readily usable for a number of research related tasks such as publishing academic works or creating web pages.
Citation searching
Users of the citation information in this database should be aware that it is incomplete. Citation information is based on a data set purchased from the Institute for Scientific Information (ISI), which consists of references from articles published by the major astronomical journals between 1980 and 1998 to articles in the same date range. From 1999 reference lists from the full-text of papers available in the ADS article service or provided to ADS by the journal publishers have been included.

Information on citing articles from ADS is now being included in the "Articles Citing this Article" tool in the Institute of Physics electronic journals (Pearce 2003).


This is a specialist database, and for astronomers and astrophysicists, it would be an invaluable research tool. For people who are not experts in the field, but are interested in the area, it is easy to use. The developers of this database have recognised that researchers not only want to find the bibliographic details of an article, but also want to have easy access to them. In astronomy, the historical literature is still relevant, and scanning the articles and making them available through this database is a great support for research. Similarly giving access to the technical information such as that found on the NED site makes this a much more useful database.

Recognition of the value of this database has come from both the library and information industry and the research and academic community. The Institute of Physics is linked to part of the information in this database, which will give the database wider exposure and recognition.

In the time I have been reviewing this database, I have worked through a network connection and a modem connection. While the network connection is better, the speed of the modem connection has been good. Using mirror sites helps spread the load, and makes the database more responsive.

My overall impression of this database is that it is a good database, giving comprehensive coverage of astronomy and astrophysics. It is easy to use, and has a number of sophisticated features to enhance the search interface.


ADS Awards and Recognition. n.d. [Online]. Available: [September 25 2003].

Eichhorn, G., et al. 2002a. Access to the Astronomical Literature through the NASA Astrophysics Data System from Developing Countries. In Library and Information Services in Astronomy IV, (ed. By B. Corbin, E. Bryson, and M. Wolf). [Online]. Available: {} [September 25 2003].

Eichhorn, G., et al. 2002b. The NASA Astrophysics Data System: free access to the astronomical literature on-line and through email. Astronomy and Space Science 282, 299-340.

Kurtz, M. J., Eichhorn, et al. 2000. The NASA Astrophysics Data System: overview. Astronomy & Astrophysics Supplement Series 143, 41-59.

Pearce, L. [] IOP's Forward Citing tool is enhanced (3/467). Private e-mail message, September 27 2003.

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