Astro VLBI

​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. 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 Mark 5 system or transported directly to the correlator through the internet (e-VLBI). We have 2 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.


Postal address:
Onsala Space Observatory
SE-439 92 Onsala


Switchboard (daytime): +46-31-772 5500
Control room: +46-31-772 5550
Fax: +46-31-772 5590

The Astro VLBI group (emails and phone):
​Michael Lindqvist Friend of VLBI​​​ +46 31-772 5508​
​Jun Yang ​Friend of VLBI ​+46 31-772 5531
Roger Hammargren​ Technical Friend of VLBI​ +46 31-772 5551​
Leif Helldner​ Technical Friend of VLBI​ +46 31-772 5576​
Karl-Åke Johansson​ Technical Friend of VLBI​ +46 31-772 5571​

EVN Call for Proposals

> recent-proposals.txt (list of observing proposals submitted to the EVN PC for the most recent deadline)

VLBI schedules

Onsala astro-VLBI schedule
> VLBI2015.txt
> VLBI2016.txt (updated 2016-09-09)
VLBI2017.txt (updated 2016-11-07)
> VLBI2018.txt (updated 2017-06-07)

Current EVN schedule

Onsala geo-VLBI schedules

Published: Fri 30 Aug 2013. Modified: Wed 07 Jun 2017