Kanzelhöhe observatory

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The Kanzelhöhe observatory in 1955 from the south. The coelostat was housed in the front tower and the back of the second tower was originally the coronograph, which was moved to the Gerlitzen summit in 1948.
Zeiss Coelostat 1941 at the Kanzelhöhe observatory: with this, the sunlight was reflected in the cellar laboratory to the drawing table and the spectrohelioscope.
Corona image from the observatory Kanzelhöhe October 12, 1947, one of the last images taken at the observatory before the coronograph was brought to the summit of the Gerlitzen.

The Kanzelhöhe observatory for solar and environmental research is a special observatory for the daily observation of solar activity . It is located in the south of Austria above the Kanzelhöhe , a 1463  m above sea level. A. high pre-summit of the Gerlitzen , about ten kilometers northeast of Villach in the federal state of Carinthia .

history

The Kanzelhöhe observatory for solar and environmental research at the University of Graz (Austria) was founded during the Second World War (construction started in 1941, completion in 1943) as one of four mountain observatories of the German Air Force . The primary task was the observation and research of solar flares and their effects on radio traffic in order to be able to provide radio advice as a result.

In the early 20th century, radio technology experienced a development spurt, and with the beginning of the Second World War it became particularly important as a component of communication and navigation technologies, especially in the military sector. However, shortwave radio in the frequency range from 3 to 30 MHz was of particular importance. These short waves are reflected by the earth's ionosphere like a mirror, which makes it possible to send signals over great distances and to communicate worldwide. At the beginning of the 1930s, Hans Mögel in Germany and John H. Dellinger in the USA recognized the connection between sudden failures in shortwave reception and radiation bursts (flares) on the sun ( Mögel-Dellinger effect ). During the Second World War, therefore, military resources began to be used for solar research in order to gain military advantages by predicting sun-related disturbances in shortwave radio.

1943 until the end of the war

On behalf of the German Air Force, Karl-Otto Kiepenheuer founded four mountain observatories by 1943: Wendelstein in Upper Bavaria, Kanzelhöhe in Carinthia, Schauinsland in the Black Forest and Zugspitze in Upper Bavaria. The Fraunhofer Institute in Freiburg / Breisgau was the headquarters . The Kanzelhöhe was characterized by its location south of the main Alpine ridge, where the weather conditions are different from those at the other locations, as well as by a high number of hours of sunshine, and the location was also accessible by a cable car . The observatory can now also be reached by car from Treffen via a well-developed toll road.

After its completion in 1943, the Kanzelhöhe observatory was opened with a celebratory colloquium. The equipment was very advanced and state-of-the-art for the time:

During the war, the following data were sent to the Fraunhofer Institute:

Prominences from the observatory Kanzelhöhe from April 11, 1959, 9:18 UT (small picture). One of the largest outbreaks of prominences observed at the observatory.

In order to improve corona observations, a new observation tower was planned on the summit of the Gerlitzen during the war , but it could no longer be completed. A new coronograph was also commissioned from Zeiss; it was supposed to be the largest and most modern coronograph in the world at the time (20 cm aperture and 3 m focal length). However, this was confiscated at the end of the war and brought to the former USSR as reparation .

After the war

After the war, the observatory of the University of Graz was assigned as a branch of the Graz University Observatory , probably because it, like the observatory, was located in the British occupation zone. The British occupiers were very interested in the continuation of the observatory and therefore built an observation tower on the summit of the Gerlitzen in 1947 to bring the coronograph there, as the observation conditions were better there. The tower of the Luftwaffe, which was not yet finished, was used by the Royal Air Force as a radio station. In 1948 this building was also handed over to the Republic of Austria, and from 1951 there was an overnight room for observers. The land on which the observatory and its outbuildings stand were used by the Air Force and later by the British occupiers without properly clarifying the ownership. Compensation through a subsequent purchase of the land did not take place until the 1950s.

At the end of the 1950s, on the occasion of the International Geophysical Year, a Zeiss Lyot - H-alpha filter was purchased, which is still in use. As the number of insects rose steadily at the summit due to the erection of radio masts and pasture farming, scientifically valuable corona observation was no longer possible due to the increased scattered light , so corona observation was finally stopped in 1963. The spectrohelioscope, on which photographic recordings could only be made with very poor quality, was dismantled in the early 1970s. A spectrograph was built from the parts of the spectrohelioscope, which can be illuminated with sunlight via a heliostat . All telescopes have been operated on the monitoring instrument in the north tower since 1973.

In 1966/67 the observatory was expanded to include workshops and in 1990 it was expanded again to include a library and a workshop. In 1954 the Sonnenvilla, a house near the old mountain station of the Kanzelbahn, was purchased for the employees.

The observatory today

Organizationally, the observatory is assigned to the dean's office of the natural science faculty of the University of Graz ; scientifically and administratively it is part of the Institute for Physics.

The study of solar activity is still one of the main tasks of the observatory, especially its effect on space weather . The area of ​​responsibility was expanded to include environmental physics and solar radiation measurements . A TAWES station of the ZAMG is also supervised.

The Kanzelhöhe observatory in 2013 with a newly built solar thermal system.

Sun observation at the observatory

The monitoring instrument (ÜWI) has served as the main solar observation instrument since 1973. The ÜWI consists of an equatorial mount on which several refractors are carried:

  • H-alpha telescope (10 cm aperture, 200 cm focal length): Through a Zeiss Lyot filter ( FWHM 0.07 nm at 656.3 nm) the chromosphere of the sun is displayed with a resolution of 2048 × 2048 pixels and a cadence of 10 Images per minute recorded with a color depth of 12 bits (4096 gray levels ). These images are immediately tested for quality and, if they are of good quality, further processed and also put online as live images. The exposure time of the recordings is adjusted automatically and is set so that bright solar flares are not overexposed. As part of the SSA program of the ESA are flares and filaments using image recognition algorithms in real time calculated.
  • White light telescope (13 cm aperture, 146 cm focal length): With a broad-band interference filter at 546 nm ( FWHM 10 nm), the photosphere of the sun with a resolution of 2048 × 2048 pixels and a rate of 3 images per minute with a Color depth of 12 bits (4096 gray levels ) recorded. The recorded images are put live online.
  • Calcium-K telescope (11 cm aperture, 165 cm focal length): Through a Lunt calcium filter (FWHM 0.25 nm at 393.7 nm) the chromosphere of the sun is displayed with a resolution of 2048 × 2048 pixels and a cadence of 10 images recorded per minute with a color depth of 12 bits (4096 gray levels). Like the others, these images will be posted live online.
  • Drawing unit (11 cm opening, 165 cm focal length): The image of the sun is projected to 25 cm in order to draw the sunspots , these spot drawings have been created since 1944 and are used to determine the sunspot relative number , a measure of solar activity . The spot numbers are forwarded daily to the Solar Influences Data Analysis Center (SIDC) of the Royal Observatory of Belgium , where the International Sunspot Number (ISN) is then generated.
  • Another H-alpha telescope with 1024 × 1024 pixel resolution and a rate of 15 images per minute that corrects the telescope tracking, which is only controlled by a simple microprocessor program. This corrects influences such as the refraction of the earth's atmosphere and the deviations due to the inclination of the ecliptic or the eccentricity of the earth's orbit.
    The surveillance instrument at the Kanzelhöhe observatory.

The Kanzelhöhe observatory is the Austrian representation in the international ISES space weather network and the European core station for solar observation within the framework of the SSA space weather program of the European space agency ESA . The observatory has been a member and data supplier for the Global High Resolution H-alpha Network since 2000.

Web links

Commons : Sonnenobservatorium Kanzelhöhe  - Collection of images, videos and audio files

Individual evidence

  1. ↑ Gundi Jungmeier, Monitoring the Sun. The early years of the Kanzelhöhe Observatory, Graz 2017; Gundi Jungmeier, Werner Pötzi, Astrid Veronig, Monitoring the Sun. The early years of the observatory Kanzelhöhe, Graz 2014, solar research on the Kanzelhöhe, in: Sterne und Weltraum, issue 8/2014.
  2. ↑ H-alpha live pictures http://cesar.kso.ac.at/main/live_im.php
  3. ↑ ESA SSA Portal KSO Federated Services
  4. ↑ H-alpha live pictures http://cesar.kso.ac.at/main/live_im.php
  5. ↑ H-alpha live pictures http://cesar.kso.ac.at/main/live_im.php
  6. ↑ International Space Environment Service http://www.ises-spaceweather.org
  7. ↑ Austrian Space Weather Page http://www.spaceweather.at
  8. ↑ Global High Resolution H-alpha Network http://swrl.njit.edu/ghn_web

Coordinates: 46 ° 40 ′ 39.1 ″  N , 13 ° 54 ′ 6 ″  E