Onsala 20 m telescope

Basic information

The 20 m diameter, radome enclosed, millimeter wave telescope in Onsala 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 Galaxy and in extragalactic objects. It is also used for astronomical VLBI observations of star forming regions, radio stars, and active galactic nuclei, and for geodetic VLBI observations to study for example crustal dynamics and polar motion. The telescope itself was built in 1975-76 and upgraded in 1992. The radome was replaced in 2014. Front-ends and back-ends are updated regularly.

Proposals for observing time are accepted from scientists from all countries.

Publication acknowledgements for Onsala 20 m data

In scientific publications containing Onsala 20 m telescope data, please

• ​Add the following sentence to the acknowledgement: "XXXX acknowledges support from Onsala Space Observatory for the provisioning of its facilities/observational support. The Onsala Space Observatory national research infrastrcuture is funded through Swedish Research Council grant No 2017-00648.";
• Give the project ID for the observations;
• When applicable, give proper references to papers about the receiver(s).

Use the following references to instrumentation papers:

• 3 mm and 4 mm receivers:
  3mm/4mm Receivers for the OSO 20-m
  Pantaleev M., Helldner, L., Pettersson, L. et al.
  Poster at the ESO ALMA Bands 2/2+3 Workshop, Chalmers, 2016
• 3 mm receiver (installed in 2014):
  A new 3 mm band receiver for the Onsala 20 m antenna
  V. Belitsky, I. Lapkin, M. Fredrixon et al.
  A&A 580, A29 (2015)
  Bibtex from ADS; doi: 10.1051/0004-6361/201425573
• 4 mm receiver:
  Optical design and verification of a 4mm receiver for the 20m telescope at Onsala Space Observatory
  Walker, George W.; Kalinauskaite, Eimante; McCarthy, Darragh N. et al.
  Proceedings of the SPIE, Volume 9914, id. 99142V 9 pp. (2016)
  Bibtex from ADS; ​doi: 10.1117/12.2232576

Handbooks

There are three handbooks available, as pdf files, for users of the 20 m telescope.​

• The OSO 20 m Telescope Handbook contains a technical overview of the telescope, observing modes, etcetera. It also includes a description of the control system Pegasus, which in 2019 was replaced by a new control system, Bifrost (described in a separate handbook).
• The BIFROST User's Handbook explains how to use the telescope control system Bifrost
• The document Onsala 20 m data properties - Important information for observers is intended for users working working with data from the 20 m telescope. It is a beta version and contains methods which are not tested in all details.

The telescope system is regularly updated, which is not always reflected in the documents above. The telescope scientist or astronomer on duty will provide observers with the latest information when needed.​​​​​​

Observing time calculator

​Please use the online observing time calculator when preparing proposals for the Onsala 20 m telescope (link to local web server at OSO)

Technical description