Radio telescopes

Onsala Space Observatory 2.3 m radio telescope - SALSA ONSALA

Salsa Onsala is a 2.3 m radio telescope operating at a wavelength of 21 cm. At this wavelength, one can observe the spiral arms of the Milky Way (our galaxy). The radio telescope can be operated remotely over the internet. To detect cosmic signals while watching the telescope move in the webcam is a great thrill for both pupils and teachers. Observations can be done during day-time as well as night-time, and even in bad weather.

Onsala Space Observatory is the Swedish National Facility for Radio Astronomy. The observatory operates the two radio telescopes in Onsala, 45 km south of Göteborg, Sweden, in the mm and cm wavelength regions, and is one of the partners in the ALMA (giant) radio-telescope in Chile.

If you are a teacher, a high-school student, or simply interested in trying SALSA and discovering the joys of radio astronomy, please contact or

At anytime you can watch the radio-telescope using the webcam (which is in the nearby control building).

How to make use of the free radio-telescope facilities

A SALSA manual (in PDF) is available in English, in French, and in Polish. Some information is available in Greek, in Italian, in Portuguese, and in Spanish.

EU-HOU has prepared exercises, including a manual that describes how to operate the antenna and how data should be processed and interpreted. Some date are accessible to get trained.

It is easy to connect to the computer in Onsala and start observing! The observations are done with the program qradio:

When you run the antenna from qradio you can see it move in the webcam. Here the telescope is in its parking position:

There is a planetarium software, kstars, that comes free with every linux distribution. When logged in to the telescope, you can use this software to point the telescope to different interesting astronomical objects.

The observations are saved into files that you can retrieve, for further analysis with SalsaJ. There is data uploaded n the Exercises section, which you can download and analyse. There is also a spreadsheet with calculations where you can add you own observations and make a better map of the Milky Way.

To observe with SalsaOnsala, EUHOU pilot school teachers should request observation time with Daniel Johansson.