For complete information regarding the International Astronomy Olympiad, please visit the IAO official homepage at http://www.issp.ac.ru/iao/. The following is excerpted from the official homepage.
Competitions for young amateur astronomers, called “Olympiads", are carried out in former USSR for many years. The first attempts to organize a competition in an international (i.e. multilanguage) scale have been done in the scientific town of Soviet Academy of Sciences “Chernogolovka" in 1990-1991 as a part of the so-called Olympiad of Naukograds and Scientific Centres (NSC Olympiad). Teams of Russia, Moscow, Latvia, and Estonia participated. These events provided ground for the future IAO proper.
Positive experience during international olympiads in other natural sciences (Physics, Chemistry, Biology), Mathematics and Informatics led to the idea of starting an International Astronomy Olympiad.
Immediately after the founding, the Olympic Coordinating Council was established.
The first official IAO was held in the Special Astrophysical Observatory of Russian Academy of Sciences in November 1996 as a part of the programme of the Autumn Astronomy School for Young Astrophysists. Notwithstanding some initial difficulties, this Olympiad was a great success and it was decided to continue with the IAO. In subsequent olympiads, the number of participating states increased.
So the Olympiad of Naukograds and Scientific Centres and Autumn Astronomy School of Young Astrophysicists in the Special Astrophysical Observatory may be considered as father and mother of the International Astronomy Olympiad.