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Kuffner Observatory, Austria

Established by Moritz von Kuffner, the observatory was constructed between 1884 and 1886 (extended in 1889/90) based on architect Franz Ritter von Neumann plans. Kuffner's intention was to create a private research institution of the highest reputation, and in order to achieve this, he spent major parts of his family's wealth on the construction, the equipment and also the ongoing operation of the observatory. Today, the Kuffner observatory still hosts its original instruments from the late 19th century, and is operated as a public observatory and educational institution jointly by the City of Vienna and the private Assiociation Kuffner Observatory.

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Geographical position

Johann Staud-Straße 10, Vienna, Austria


Latitude : 16º 17,8’ east, Longitude: 48º 12,8’ north, 302 meters above sea level

General description

The Kuffner observatory in 1891, immediately after

The Kuffner observatory in 1891, immediately after its extension. Reproduced from original photo in the Ottakring district museum

The observatory, located in the outskirts of the Viennese district of Ottakring, was built between 1884 and 1886, and extended in 1889/90. From the start it hosted astronomical instruments of the highest quality and earned international reputation.

From the opening until the beginning of World War I, the observatory contributed major results to the scientific community. The sudden death of its then-acting director Leo de Ball and the beginning of World War I forced the operation to be stalled.

In between the World Wars, attempts to reinitiate operations were unsuccessful, and shortly before World War II, the Kuffner family was forced to flee from Austria to Switzerland.

In 1947 the observatory was reopened (on a provisional state) as a public educational institution, but only since the 1980ies, an increasingly permanent operation as public educational and sky-gazing institute could be established. After granting the nessessary funding in the early 1990ies by City of Vienna, the much needed general restauration could be undertaken, with a first milestone reached in 1995 by reopening the observatory to the public on a regular schedule.

Brief inventory

The original astronomical equipment of the Kuffner Observatory could be preserved despite the aryanization of the observatory and subsequent changes in ownership. As of today, the observatory and all its instruments are fully refurbished and operational.

The great refractor

Main telescope, built by Repsold & Söhne (Ham

Main telescope, built by Repsold & Söhne (Hamburg), optics by Steinheil & Söhne (Munich). Image copyright Haeferl, license cc-by-sa-3.0-at

The heliometer

Heliometer, built by Repsold & Söhne (Hamburg

Heliometer, built by Repsold & Söhne (Hamburg), optics by Steinheil & Söhne (Munich). Image copyright Haeferl, license cc-by-sa-3.0-at

The meridian circle

Meridian circle, built by Repsold & Söhne (Ha

Meridian circle, built by Repsold & Söhne (Hamburg), optics by Steinheil & Söhne (Munich). Image copyright Haeferl, license cc-by-sa-3.0-at

The vertical circle

Vertical circle, built by Repsold & Söhne (Ha

Vertical circle, built by Repsold & Söhne (Hamburg), optics by Steinheil & Söhne (Munich). Image copyright Haeferl, license cc-by-sa-3.0-at

Other instruments at the observatory

  • High precision pendulum clock "Urban No. 18", mainly used with the meridian and vertical circle observations, but also with the main refractor and heliometer.
  • Aparatus for surveying the photographic plates
  • A ’Positionsfadenmikrometer’ to precisely measuring small angles when using the Heliometer or the main refractor


The observatory looks back on a very changeful history, with five different periods in its 130 years (1886 to 2015) of continuity.

The observatory as a scientific institution (1886 to 1913)

The main scientific task of the observatory was to survey the sky (stellar positions, time keeping, measuring star distances). The observatory, together with the Strasbourg, the Washington and the Cambridge observatories joined the international effort to survey all stars down to magnitude 9 with the highest available precision. The Kuffner Observatory was responsible for those 8.468 stars located in the area from declination -6° to declination -10° . This was the first southern zone to be completed and got published in 1904. Only in 1912 Cambridge Observatory published it’s results as the last southern zone.

The high quality of work soon received international recognition. A number of international institutions decided to exchange publications with the Kuffner Observatory, namely the "k. Akademie der Wissenschaften", Vienna, the "Académie royal de Belgique", the "Royal Society", London, the "Royal Astronomical Society", the "Astronomical Society of the Pacific", the "Società degli spettroscopisti italiana", the "Circolo matematico di Palermo", the "Recheninstitut der Kgl. Sternwarte", Berlin, the "Specula Vaticana" and the observatories at Cambridge U. S., Cambridge (England), Paris, Potsdam and Pulkowo.

In 1896 Leo de Ball initiated studies on errors regarding the heliometer scales, the focus and dependencies on temperature. The results were used to start a major stellar parallax program with 252 stars from 2 mag to 6 mag. De Ball convinced other observatories like Bamberg and Göttingen, as well as the Yale Observatory to join in on this program. By 1908 the Kuffner Observatory published 16 stellar parallaxes. At this time, only a total of about 100 stellar (including those published by the Kuffner Observatory) parallaxes were known and published.

Karl Schwarzschild intensely used the great refractor to advance the use of photography in astrometric work. He developed the method to determine the absolute magnitude of stars from photographic exposures. During this work, he discovered the Schwarzschild law regarding the accurate calculation of optical density in photographic material.

World Wars I and II (1913 to 1946)

In 1916 Leo de Ball, then director of the observatory died. The WW-I environment made it impossible for Moritz von Kuffner to further support the observatory and find a new director. Thus the scientific projects were terminated unfinished. The von Kuffner family, being jewish, was forced to sell their properties in Vienna and flee from Austria.

Revitalisation as public observatory (1947 to 1979)

In this period a number of plans were developed to revitalise the observatory.

Planning for the future and restauration (1980 to 1995)

In this timeperiod the efforts of private citicens (namely the members of the private assiociation ’Verein Kuffner Sternwarte’) to preserve the observatory was crutial to its survival. Besides an increasingly regular calender of public tours, the main task was to convince local politics to provide funding for restauration and an ongoing operation of the observatory. In the early 1990ies the City of Vienna approved (and funded) the complete restauration of the observatory.

Implementing and ensuring permanent operations (1995 to 2015)

As a major milestone in the history of the observatory, in 1995 the institute was reopened as a public outreach institution. The responsibility for the operation was divided between the private assiocation "Verein Kuffner Sternwarte" and the (city-owned) public-education organisation "Volkshochschule Wien".

Present use

The observatory is used for public education by the two operating entities (VHS Wien and Verein Kuffner Sternwarte). Together the two organisations provide a 7-days-a-week service to the public, with public observing nights and educational presentations almost every day in the year.

State of conservation

After an extensive restauration in the early 1990ies, that probably costed the City of Vienna some 2 million Euros, the observatory today presents itself in a fairly well preserved state. The instruments are well protected and maintained. In 2018, thanks to a generous grant by the great-grandchildren of Moritz von Kuffner, both the main refractor and the Heliometer received a major maintenance and restauration service.

Main threats or potential threats

As with probably most non-mainstream educational institutions, financial support from governmental agencies is becomming increasingly difficult. The ongoing operation seven-days-a-week is demanding a lot of time and enthusiams from the volunteers responsible for this operation.


In 1977 the observatory became listed under the austrian preservation order act. This step prevented existing plans to break down the observatory and build three residential buildings from being executed.

Links to external sites

Links to external on-line pictures

Wikipedia Commons

Bibliography (books and published articles)

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About the author

Rüdiger Schultz lives in Vienna (Austria)


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