Iso-Heikkilä Observatory

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Iso-Heikkilä Observatory
Iso-Heikkilan tahtitorni talvi.jpg
Organization Turun Ursa ry
Code 062  
Location Iso-Heikkilä, Turku, Finland
Coordinates 60°27′7″N 22°13′47″E / 60.45194°N 22.22972°E / 60.45194; 22.22972Coordinates: 60°27′7″N 22°13′47″E / 60.45194°N 22.22972°E / 60.45194; 22.22972
Established 1937 (1937)
unnamed 15 cm telescope
unnamed 13 cm telescope
unnamed 19 cm Schmidt-Väisälä camera

Iso-Heikkilä Observatory (Finnish: Iso-Heikkilän tähtitorni) is an amateur astronomical observatory in the Iso-Heikkilä district of Turku, Finland. It was operated by the University of Turku from 1937 to 1972 but is now used by a local division of Ursa Astronomical Association.


The observatory was originally owned by the department of astronomy of the University of Turku. It was built in 1935 and 1936, and technically designed by physics and astronomy professor Yrjö Väisälä. Väisälä's research team discovered a total of 807 minor planets and 7 comets in the observatory. Väisälä also contributed significantly to research in the areas of optics and surveying.

As the city expanded and a steel factory was built under a kilometer away from the observatory, the astronomy department of the university moved to Tuorla Observatory in the 1950s. Iso-Heikkilä remained in the use of students for some time, until the university gave up its ownership completely in 1972. The observatory is now used by the Turku department of Ursa Astronomical Association and owned by the city of Turku.

In the 1960s, an apartment building area was built in Iso-Heikkilä, preventing any observations of low-sky objects in all directions except north.

Instruments and facilities[edit]

The observatory has two 6-meter domes in the East-West direction. The main instruments of the association are located in the western dome: the 15 and 13 centimeter telescopes made by Yrjö Väisälä and a 19 cm Schmidt-Väisälä camera. In the past, the dome has housed a 50 centimeter wide-angle camera which is nowadays located in the Kevola Observatory – it was the telescope used to discover the aforementioned minor planets and comets.

Datum line[edit]

In the forest further away from the observatory, about 200 metres (660 ft) to the northeast, is a concrete pillar used by Yrjö Väisälä in the 1940s in his datum line measurements. The Väisälä comparator has been used in important datum line measurements around the world.

Another pillar that remains today is located 500 metres (1,600 ft) to the southwest from the previous one, across the railway.