The Onsala Space Observatory (OSO) (formerly Råö Space Observatory), also known as the Swedish National Facility for Radio Astronomy, is a space observatory operating two radio telescopes in Onsala, Sweden, about 45 km south of Gothenburg. The observatory has been, since 1990, the national facility for radio astronomy in Sweden.
The observatory was founded in 1949 by professor Olof Rydbeck. It is currently hosted by the Department of Earth and Space Science at Chalmers University of Technology and is operated on behalf of the Swedish Research Council.
Instruments[]
- Two radio telescopes: Two radio telescopes of 20 and 25 m are present at the observatory. They are used to study the birth and death of stars, and molecules in the Milky Way and other galaxies
- A LOFAR station: The Swedish station in the international radio telescope LOFAR is located at Onsala Space Observatory and was completed in 2011.
- VLBI: Telescopes in different countries are linked together for better resolution.
- APEX: Radio telescope in Chile for sub-millimeter waves. Used for research about everything from planets to the structure of the Universe.
- Odin: A satellite for studies of things such as the Earth's atmosphere and molecular clouds in the Milky Way.
- Space geodesy: Radio telescopes (VLBI) and satellites (GPS) are used to measure movements in Earth's crust and water vapour in the atmosphere.
- Receiver development: Laboratories for development of sensitive radio receivers.
- Event Horizon Telescope: A project to create a large telescope array for observing the immediate environment of the Milky Way's supermassive black hole, Sagittarius A*.
Directors[]
- 1949-1979: Olof Rydbeck
- 1981-2005: Roy Booth
- 2005-2013: Hans Olofsson
- 2013-present: John Conway
25-meter telescope[]
The 25.6 m diameter, polar mount decimeter-wave telescope is equipped with receivers for frequencies of up to 7 GHz, and is used for VLBI observations. It is also operated as a single dish for studies of molecular clouds in the Milky Way galaxy. It was completed in 1963.
20-meter telescope[]
The 20 m diameter millimeter wave telescope is equipped with receivers for frequencies up to 116 GHz. It is used for observations of millimeter wave emission from molecules in comets, circumstellar envelopes, and the interstellar medium in the Milky Way galaxy and extragalactic objects. The telescope is enclosed in a radome.
It is also used for astronomical VLBI observations of star forming regions, radio stars, and active galactic unceli, and for geodetic VLBI observations to study e.g. crustal dynamics and polar motion. The telescope was completed in 1975 and was upgraded in 1992.
It is also used, as part of the European and worldwide networks, for astronomical Very Long Baseline Interferometry (VLBI) observations of star forming regions, radio stars, and active galactic nuclei, and for geodetic VLBI observations to study e.g. crustal dynamics and polar motion.
Receivers[]
The telescope is equipped with the following receivers:
| Frequency range | Receiver temperature | Receiver type | Polarization |
|---|---|---|---|
| 2.2–2.4 GHz | 60 K | HEMT amplifier | Single |
| 8.2–8.4 GHz | 80 K | HEMT amplifier | Dual |
| 18.0–26.0 GHz | 30 K | HEMT amplifier | Dual |
| 26.0–36.0 GHz | 50 K | HEMT amplifier | Single |
| 36.0–49.8 GHz | 50 K | HEMT amplifier | Dual |
| 85–116 GHz | 80–130 K | SIS mixer | Single |
LOFAR station[]
A LOFAR station is present in the observatory. The station was completed on September 26, 2011. The station consists of 192 small antennas, which work together to receive space radio emission. The registered signals are transmitted via a fiber-optic communication line to the Netherlands, where they are combined with the signals received from the remaining 47 LOFAR stations.
The LOFAR is primarily used for solving scientific problems and other activities, such as:
- Long wave sky surveys and accurate catalogs of radio sources (MSSS project)
- Detection of extremely weak emission of neutral hydrogen at a wavelength of 21 cm, at redshifts corresponding to the epoch of the universe before the formation of the first stars and galaxies (project "Age of Reionization")
- Pulsar research
- Long wave mapping
The presentation of the first scientific result and the first announcement of applications for observations with the LOFAR telescope took place on January 10, 2012. An image of the Cygnus A galaxy was obtained at a frequency of 240 MHz.