European Cultural Heritage Online
More than 300,000 high resolution images of historical sources, with collections in history of cosmology, history of mechanics, history of science, the scientific revolution, etc.
The ARI Bibliographical Database for Astronomical References (ARIBIB) of the Astronomisches Rechen-Institut (Heidelberg) is the complete electronic version of the Astronomischer Jahresbericht, which listed the world’s astronomical publications from 1899–1968 and Astronomy and Astrophysics Abstracts, which covered the period 1969–2000.
Google Scholar Broad search capabilites. The advanced version allows you to be more precise.
Institute of Physics Journals
Many journals, including the Astronomical Journal since 1998, the Journal of Physics, and Chinese, European, and Russian journals. Mostly recent, but historic issues of some, such as Journal of Scientific Instruments and Transactions of the Optical Society. Costly.
Includes hundreds of thousands of chapters, articles, books, etc.. Some are “Open Access” (free), but most are costly.
Wiley Online Library
Includes Annalen der Physik, Annals of the New York Academy of Science, Astronomische Nachrichten, Astronomy & Geophysics, and a number of others. Note that some are costly here but free on ADS.
Sponsored by the History of Science Society, it contains history of science, medicine, and technology, and their cultural influences. All articles are available—at a cost. Tables of contents and searching are free.
Journal of Astronomical History and Heritage The JAHH, published three times per year. All content back to 1998 is now available free on this site and also on ADS. Since 2012 the journal is published in electronic format only, but it is possible to download and print entire issues as well as individual papers from the JAHH site.
AAS Obituary Index
Links to all obituaries published in the Bulletin of the American Astronomical Society. The obituaries are in ADS and are free.
The MacTutor History of Mathematics archive Extensive biographies and essays on historical topics. The definition of mathematicians is sufficiently elastic to include Edwin Hubble, and the topics include mathematical astronomy.
The Bruce Medalists
Photos, brief biographies, and extensive bibliographies of more than 100 astronomers honored since 1898 by the Astronomical Society of the Pacific.
The Galileo Project
Information on the life and work of Galileo Galilei and his contemporaries.
Some aspects of the early history of astronomy, drawing on the collection of instruments and books at the University of Cambridge, mostly from medieval times through Kepler.
Carnegie Institution Year Books
All of the year books of the Carnegie Institution for Science (formerly the Carnegie Institution of Washington) are available online. They include reports of the Mount Wilson Observatory.
American Physical Society Forum on the History of Physics
The Forum on the History of Physics, a member unit of the American Physical Society, was founded in 1980 to bring together physicists, historians, and other members of APS with an interest in the history of their subject and the impact of that history on culture, education, and physics research itself.
Antique Telescope Society
The Antique Telescope Society, Inc. is organized and operated exclusively for educational and/or scientific purposes. The purpose of the Society is to unite colleagues interested in antique telescopes, binoculars instruments, books, atlases and related items, and to promote the membership's interests in astronomical history and discovery, the history of optics, and the preservation and use of the antique instruments through stewardship and education.
British Society for the History of Science
The main organisation in the British Isles working to bring together people with an interest in the histories of science, technology and medicine and their changing relationship with society.
History of Science Society
The History of Science Society is the world's largest society dedicated to understanding science, technology, medicine, and their interactions with society in historical context.
Inter-Union Commission on the History of Astronomy
The Inter-Union Commission on the History of Astronomy is a joint Commission of the IAU and the International Union of the History and Philosophy of Science, Division of Science and Technology (IUHPS/DHST). The ICHA was founded in 2001 in order to create a Commission that involves and represents all historians of astronomy–including scholars who, being primarily historians rather than astronomers, are not members of the IAU. All members of C41 are, ipso facto, members of the ICHA.