The '''SAO/NASA Astrophysics Data System''' ('''ADS''') is an [[online database]] of over 16 million [[astronomy]] and [[physics]] papers developed by the [[National Aeronautics and Space Administration]] (NASA) on [[Astronomy & Astrophysics|astronomy]] and [[physics]]. [[abstract (summary)|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 review]]ed and/or non-peer-reviewed sources. ADS is managed by the [[Smithsonian Astrophysical Observatory]].
Since its beginning in 1992, ADS is a powerful research tool withthat has significant impact on the efficiency of astronomical research since it was started in 1992.<ref name="announcement">{{cite journal |last=Kurtz |first=M.J. |display-authors=et al. |year=1993 |title=Intelligent Text Retrieval in the NASA Astrophysics Data System |journal=Astronomical Data Analysis Software and Systems II |volume=52 |page=132 |bibcode=1993ASPC...52..132K}}</ref> BecauseADS itsalso searchgreatly enginereduces isthe customizedtime forit astronomicalused needs,to ADSor greatlynormally reduceswould the timetake to complete literature searches, whichdue wouldto commonlythe takefact daysit oris weekscustomized specifically for astronomical needs. Studies have found that the monetary benefit to astronomy that ADS savescontributes is equivalent to several hundred million in [[USD|US dollars]] annuallyevery year (2005).<ref name="overview" /><ref name='"impact'">{{cite journal |last=Kurtz |first=M.J. |author2=Eichhorn G. |author3=Accomazzi A. |author4=Grant C.S. |author5=Demleitner M. |author6=Murray S.S. |year=2005 |title=Worldwide Use and Impact of the NASA Astrophysics Data System Digital Library |journal=Journal of the American Society for Information Science and Technology |volume=56 |issue=1 |pages=36–45 |arxiv=0909.4786 |bibcode=2005JASIS..56...36K |doi=10.1002/asi.20095 |s2cid=15181632}} ([http://cfa-www.harvard.edu/~kurtz/jasis-abstract.html Preprint])</ref>
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.
ADS is used among [[astronomer]]s worldwide, and therefore ADS usage statistics can be used to analyze global trends in astronomical research. These studies have revealed that the amount of research an astronomer carries out is related to the per capita [[gross domestic product]] (GDP) of the country in which the scientist is based, and that the number of astronomers in a country is proportional to the GDP of that country. Consequently, the total amount of research done in a country is proportional to the square of its GDP divided by its population.<ref name="impact">{{cite journal |last=Kurtz |first=M.J. |author2=Eichhorn G. |author3=Accomazzi A. |author4=Grant C.S. |author5=Demleitner M. |author6=Murray S.S. |year=2005 |title=Worldwide Use and Impact of the NASA Astrophysics Data System Digital Library |journal=Journal of the American Society for Information Science and Technology |volume=56 |issue=1 |pages=36–45 |doi=10.1002/asi.20095 |bibcode=2005JASIS..56...36K |arxiv=0909.4786 |s2cid=15181632}} ([http://cfa-www.harvard.edu/~kurtz/jasis-abstract.html Preprint])</ref>
