Astrophysics Data System
The SAO/NASA Astrophysics Data System (ADS) is an online database of over 15 million records of publications developed by the National Aeronautics and Space Administration (NASA) on astronomy and physics. Abstracts are freely available for most articles, and fully scanned articles may be available in Graphics Interchange Format (GIF) and Portable Document Format (PDF). Hosted papers may be from peer reviewed or non-peer-reviewed sources. ADS is managed by the Smithsonian Astrophysical Observatory.
Producer
Smithsonian Astrophysical Observatory for the National Aeronautics and Space Administration (United States)
1992 to present
Free
Index & abstract & full-text
Worldwide
Beginning in 1992, ADS is a research tool that improves astronomical research, and is specifically tailored to astronomical needs.[1] The monetary benefit to astronomy that ADS contributes is equivalent to several hundred million in US dollars every year (2005).[2][3]
The SAO/NASA Astrophysics Data System (ADS) usage statistics can be used to analyze global trends in astronomical research due to it being used amongst astronomers worldwide. Those statistics revealed the direct correlation between both the number of astronomers and the amount of research an astronomer carries out and the per capita gross domestic product (GDP) of the country from where the scientist is based.
History[edit]
The importance of recording and classifying earlier astronomical knowledge and works was recognized in the 18th century, with Johann Friedrich Weidler publishing the first comprehensive history of astronomy in 1741 and the first astronomical bibliography in 1755. This effort was continued by Jérôme de La Lande, who published his Bibliographie astronomique in 1803, a work that covered the time from 480 B. C. to the year of publication. The Bibliographie générale de l’astronomie, Volume I and Volume II were published by J.C. Houzeau and A. Lancaster in Brussels, followed in the 1882 to 1889 period.[4][5]
As the number of astronomers and astronomical publications grew, bibliographical efforts became institutional tasks, first at the Observatoire Royal de Belgique, where the Bibliography of Astronomy was published from 1881 to 1898, and then at the Astronomischer Rechen-Institut in Heidelberg, where the yearly Astronomischer Jahresbericht was published from 1899 to 1968. After this date it was replaced by the Astronomy and Astrophysics Abstracts yearly book series which continued until the end of the 20th century.
During the 1980s, however, astronomers realized that the nascent technologies which formed the basis of the Internet could be used to build an electronic indexing system of astronomical research papers, which could allow astronomers to make extensive searches of the existing literature on any given research topic, as well as to keep abreast of a much greater range of research.[6]
The first suggestion of a database of journal paper abstracts was made at a conference on Astronomy from Large Data-Bases held in Garching bei München in 1987.[7][8][9][10] Initial development of an electronic system for accessing astrophysical abstracts took place during the following five years. In 1991 discussions took place on how to integrate ADS with the SIMBAD database, containing all available catalog designations for objects outside the Solar System, to create a system where astronomers could search for all the papers written about a given object.[2]
An initial version of ADS, with a database consisting of 40 papers, was created as a proof of concept in 1988. The ADS Abstract Service was announced in November 1992 [1] and was released for general use in April 1993. The ADS database was successfully connected with the SIMBAD database in the summer of 1993. The creators believed this was the first use of the Internet to allow simultaneous querying of transatlantic scientific databases. Until 1994 the service was available via proprietary network software, but it was transferred to the nascent World Wide Web early that year. The number of users of the service quadrupled in the five weeks following the introduction of the ADS web-based service.[2]
At first, the journal articles available via ADS were scanned bitmaps created from the paper journals, but from 1995 onwards, the Astrophysical Journal began to publish an on-line edition, soon followed by the other main journals such as Astronomy and Astrophysics and the Monthly Notices of the Royal Astronomical Society. ADS provided links to these electronic editions from their first appearance. Since the year 1995, the number of ADS users has doubled roughly every two years. ADS now has agreements with almost all astronomical journals, who supply abstracts. Scanned articles from as far back as the early 19th century are available via the service, which now contains over fifteen million documents.
In 2011 the ADS launched ADS Labs Streamlined Search which introduced facets for query refinement and selection. In 2013 ADS Labs 2.0 featuring a new search engine, full-text search functionality, scalable facets and an API was introduced. In 2015 the new ADS, codenamed Bumblebee, was released as ADS-beta. The ADS-beta system features a microservices API and client-side dynamic page loading served on a cloud platform. In May 2018 the beta label was dropped and Bumblebee became the default ADS interface—with some legacy features (ADS Classic) remaining available.[11] Development continues to the present day, with an extensible API available: enabling users to build their own utilities on top of the ADS bibliographic record.
The ADS service is distributed worldwide, with twelve mirror sites in twelve countries, with the database synchronized by weekly updates using rsync, a mirroring utility which allows updates to only the portions of the database which have changed. All updates are triggered centrally, but they initiate scripts at the mirror sites which "pull" updated data from the main ADS servers.[12]
Software and hardware[edit]
The software runs on a system that was written specifically for it, allowing for extensive customization for astronomical needs that would not have been possible with general purpose database software. The scripts are designed to be as platform independent as possible, given the need to facilitate mirroring on different systems around the world, although the growing use of Linux as the operating system of choice within astronomy has led to increasing optimization of the scripts for installation on that platform.[12]
The main ADS server is located at the Center for Astrophysics | Harvard & Smithsonian in Cambridge, Massachusetts, and is a dual 64-bit X86 Intel server with two quad-core 3.0 GHz CPUs and 32 GB of RAM, running the CentOS 5.4 Linux distribution.[13] Mirrors are located in Brazil, China, Chile, France, Germany, India, Indonesia, Japan, Russia, South Korea, United Kingdom, and Ukraine.[15]
Indexing[edit]
ADS currently (2005) receives abstracts or tables of contents from almost two hundred journal sources. The service may receive data referring to the same article from multiple sources, and creates one bibliographic reference based on the most accurate data from each source. The common use of TeX and LaTeX by almost all scientific journals greatly facilitates the incorporation of bibliographic data into the system in a standardized format, and importing HTML-coded web-based articles is also simple. ADS utilizes Python and Perl scripts for importing, processing and standardizing bibliographic data.[12]
The apparently mundane task of converting author names into a standard Surname, Initial format is actually one of the more difficult to automate, due to the wide variety of naming conventions around the world and the possibility that a given name such as Davis could be a first name, middle name or surname. The accurate conversion of names requires a detailed knowledge of the names of authors active in astronomy, and ADS maintains an extensive database of author names, which is also used in searching the database (see below).
For electronic articles, a list of the references given at the end of the article is easily extracted. For scanned articles, reference extraction relies on OCR. The reference database can then be "inverted" to list the citations for each paper in the database. Citation lists have been used in the past to identify popular articles missing from the database; mostly these were from before 1975 and have now been added to the system.
Coverage[edit]
The database now contains over fifteen million articles. In the cases of the major journals of astronomy (Astrophysical Journal, Astronomical Journal, Astronomy and Astrophysics, Publications of the Astronomical Society of the Pacific and the Monthly Notices of the Royal Astronomical Society), coverage is complete, with all issues indexed from number 1 to the present. These journals account for about two-thirds of the papers in the database, with the rest consisting of papers published in over 100 other journals from around the world, as well as in conference proceedings.[13]
While the database contains the complete contents of all the major journals and many minor ones as well, its coverage of references and citations is much less complete. References in and citations of articles in the major journals are fairly complete, but references such as "private communication", "in press" or "in preparation" cannot be matched, and author errors in reference listings also introduce potential errors. Astronomical papers may cite and be cited by articles in journals which fall outside the scope of ADS, such as chemistry, mathematics or biology journals.[16]
Impact on astronomy[edit]
ADS is almost universally used as a research tool among astronomers, and there are several studies that have estimated quantitatively how much more efficient ADS has made astronomy; one estimated that ADS increased the efficiency of astronomical research by 333 full-time equivalent research years per year,[2] and another found that in 2002 its effect was equivalent to 736 full-time researchers, or all the astronomical research done in France.[3] ADS has allowed literature searches that would previously have taken days or weeks to carry out to be completed in seconds, and it is estimated that ADS has increased the readership and use of the astronomical literature by a factor of about three since its inception.[3]
In monetary terms, this increase in efficiency represents a considerable amount. There are about 12,000 active astronomical researchers worldwide, so ADS is the equivalent of about 5% of the working population of astronomers. The global astronomical research budget is estimated at between 4,000 and US$5,000 million,[20] so the value of ADS to astronomy would be about 200–250 million USD annually. Its operating budget is a small fraction of this amount.[3]
The great importance of ADS to astronomers has been recognized by the United Nations, the General Assembly of which has commended ADS on its work and success, particularly noting its importance to astronomers in the developing world, in reports of the United Nations Committee on the Peaceful Uses of Outer Space. A 2002 report by a visiting committee to the Center for Astrophysics, meanwhile, said that the service had "revolutionized the use of the astronomical literature", and was "probably the most valuable single contribution to astronomy research that the CfA has made in its lifetime".[21]
Sociological studies using ADS[edit]
Because it is used almost universally by astronomers, ADS can reveal much about how astronomical research is distributed around the world. Most users access the system from institutes of higher education, whose IP address can easily be used to determine the user's geographical location. Studies reveal that the highest per-capita users of ADS are France and Netherlands-based astronomers, and while more developed countries (measured by GDP per capita) use the system more than less developed countries; the relationship between GDP per capita and ADS use is not linear. The range of ADS usage per capita far exceeds the range of GDP per capita, and basic research carried out in a country, as measured by ADS usage, has been found to be proportional to the square of the country's GDP divided by its population.[3] Statistics also imply that there are about three times as many astronomers in countries of European culture as in countries of Asian cultures, perhaps suggesting cultural differences in the importance attached to astronomical research.[3] The amount of basic research carried out in a country is found to be proportional to the number of astronomers in that country multiplied by its GDP per capita, with considerable scatter.
ADS has also been used to show that the fraction of single-author astronomy papers has decreased substantially since 1975 and that astronomical papers with more than 50 authors have become more common since 1990.[22]