Astronomical Very Long Baseline Interferometry (VLBI)
(For EVN Call for Proposals, see below.)
High spatial resolution, i.e., images with fine details, requires large telescopes. The highest resolution in radio astronomy is achieved by using several radio telescopes, often in different countires or even on different continents, which simultaneously observe the same celestial objects. The data from all telescopes are sent to a central processor where images of the observed sourced can be produced. The technique is called Very Long Baseline Interferometry (VLBI). The same technique can also be used to study the Earth: distances between continents can be measured very accurately and Earth's rotation rate can be determined.
Onsala Space Observatory is active in VLBI research. Astronomical VLBI observations are made with the 20 m and 25 m telescopes, and geodetic VLBI observations with the 20 m telescope and the Onsala Twin Telescope (OTT). The observatory is a member of the European VLBI Network (EVN), the Global mm-VLBI Array, and the International VLBI Service for Geodesy & Astrometry (IVS).
The VLBI back-end consists of digital base band converters (DBBC). Data is recorded on the Flexbuff system or transported directly to the correlator through the internet (e-VLBI). We have two parallell VLBI systems and can observe with the 20 m and 25 m telescope in VLBI-mode simultaneously.
The Onsala 25 m telescope participated already in 1968 in the first transatlantic VLBI experiment. In January 2004, the first e-VLBI experiment took place between Onsala Space Observatory and radio telescopes in Westerbork, Holland, and Cambridge, England.
Onsala Space Observatory
SE-439 92 Onsala
Switchboard (daytime): +46-31-772 5500
Control room: +46-31-772 5550
Fax: +46-31-772 5590The Astro VLBI group (emails and phone):
The European VLBI Network (EVN)
Using the EVN (incl. Call for Proposals)
Onsala astro-VLBI schedule
> VLBI2016.txt (updated 2016-09-09)
> VLBI2017.txt (updated 2016-11-07)
> VLBI2018.txt (updated 2017-08-08)
> VLBI2019.txt (updated 2018-09-28)
> VLBI2020.txt (updated 2019-07-11)
> VLBI2021.txt (updated 2020-07-01)
Current EVN block schedule
Onsala geo-VLBI schedules