INTERNATIONAL

• International Astronomical Union (IAU)
• European Southern Observatory (ESO)
• International Ultraviolet Explorer (IUE)

Austria

• Wien - Institute for Astronomy at the University of Vienna

Bulgaria

• Rozhen Observatory - unofficial

Czech Republic

• Ceska astronomicka spolecnost 
• Brno - Astronomicky ustav MU
• Brno - Hvezdarna a planetarium Mikulase Kopernika
• Ceske Budejovice - Hvezdarna a planetarium
• Klet - hvezdarna
• Ondrejov - AsU AV CR
• Ostrava - Hvezdarna a Planetarium
• Praha - AU MFF UK 
• Praha - Hvezdarna a planetarium hlavniho mesta Prahy (Stefanikova hvezdarna, Planetarium Praha, Hvezdarna Dablice)
• Upice - Hvezdarna
• Valasske Mezirici - Hvezdarna
• Vlasim - Hvezdarna

Estonia

• Toravere - Tartu Observatory

France

• Meudon - Observatoire de Paris
• Nice - Observatoire de Cote d'Azur

Germany

• Garching - Max-Planck-Institut fuer Astrophysik
• Garching - Max-Planck-Institut fuer Extraterrestrische Physik
• Hamburg - Hamburger Sternwarte
• Heidelberg - Landessternwarte Koenigstuhl 
• Heidelberg - Max-Planck-Institut fuer Astronomie
• Kiel - Institute of Astronomy and Astrophysics
• Muenchen - Universitaetssternwarte
• Potsdam - Lehrstuhl Astrophysik
• Potsdam - Astrophysikalisches Institut (AIP)
• Wendelstein - Observatory

Hungary

• Konkoly Observatory

Netherlands

• Universiteit Utrecht

Norway

• Tromso - Nordlysobservatoriet - Universitetet i Tromso (The Auroral Observatory - University of Tromso)

Russia

• Kazan - Kazan State University, Department of Astronomy

Slovakia

• Slovenska astronomicka spolocnost
• Tatranska Lomnica - AsU SAV

Spain

• Instituto de Astrofisica de Canarias

Sweden

• Uppsala - Astronomical Observatory

USA

• American Astronomical Society (AAS)
• The Astronomical Society of the Pacific (ASP)
• Bartol Research Institute
• Kitt Peak National Observatory (KPNO)
• National Aeronautics and Space Administration (NASA)
• Goddard Space Flight Center (GSFC)
• Jet Propulsion Laboratory (JPL)

LISTS OF WWW SERVERS

• Astronomical Departments
• Astronomical Societies
• Space Agencies