Disseminates astronomical information. The ASP has become the largest general astronomy society in the world, with members from over 70 nations.

a non-profit organization dedicated to being a catalyst and information source for all those interested in research and education using relatively small astronomical telescopes.

was established to encourage and facilitate the observation of occultations and eclipses. It provides predictions for grazing occultations of stars by the Moon and predictions for occultations of stars by asteroids and planets, information on observing equipment and techniques, and reports to the members of observations made.

An association founded under the Swiss Civil Code in 1990. Its purpose is to contribute to and promote the advancement of astronomy in Europe.

Promotes international interdisciplinary programs in solar-terrestrial physics, and organizes and coordinates such programs. Site has a newsletter, meetings and events, member directory, announcements, and links to related groups.

Established 1899, AAS is the major professional organization in North America for astronomers, other scientists and individuals interested in astronomy.

Maintains the development of astronomy and reinforces scientific contacts between astronomers of the former Soviet Union and their colleagues all over the world. Includes summaries of previous meetings and activities in which the group participates. In Russian and English.

Works to maintain the International Celestial Reference System and Frame, and the International Terrestrial Reference System and Frame, and to provide timely and accurate data on the Earth's orientation for current use and long-term studies. Site describes the group's structure and function.