An observatory desinged and built by professor Väisälä
was finished in Iso-Heikkilä, Turku, in autumn 1937. Before,
astronomical observations had been made at an observatory of Ursa of Turku,
a local association of amateur astronomers. The largest one in Finland,
a 36-centimetre telescope was build in Iso-Heikkilä.
Yrjö Väisälä and his staff observed the vast
number of 801 new asteroids at Iso-Heikkilä Observatory. Turku
became the most active asteroid hunter in the world. Orbit was calculated
for 123 new asteroids.