Call for proposals

Observati​ons with APEX, the Onsala 20 m telescope, and the Swedish LOFAR station 

Due to the corona virus situation and its effect on observations, the spring Call for Proposals for observations with APEX (Swedish time), the Onsala 20 m telescope, and the Swedish LOFAR station (stand-alone mode) has been cancelled. The next Call for Proposals will be announced after the summer.


Last Call fo​r proposals (deadline 18 October 2019)
(For EVN Call for Proposals, see the Astro VLBI page. For proposals for Directors Discretionary Time (DDT), see below.)

Proposals are invited for observations with the APEX telescope, the Onsala Space Observatory 20 m telescope, and the Swedish LOFAR station in stand-alone mode, in the observing period April – ​August 2020.

Deadline: Friday 18 october 2019 (23:59:59 UTC)
(If you are considering submitting close to the deadline, please note that support will only be available during normal office hours.)

Proposals are to be submitted through the NorthStar system.


APEX, the Atacama Pathfinder EXperiment, is a 12 m diameter submillimetre telescope at 5100 m altitude on Llano Chajnantor in Chile.

The receivers offered in this Call are the heterodyne receivers SEPIA (ALMA band 5, 159-211 GHz; band 7, 272-376 GHz; and band 9, 578-738 GHz) and nFLASH (ALMA band 6, 200-270 GHz; and band 8, 385-500 GHz), and the bolometer arrays ArTeMiS (350 and 450 μm) and LABOCA (870 μm).

In general, proposals for Swedish time on APEX must have at least one co-I with a Swedish affiliation; however a maximum of 20% of the observing time will be open to international proposals (i.e. those without a PI or co-I with a Swedish affiliation) - to be scheduled based purely on scientific merit.

More information about APEX proposals.

Onsala 20 m

The Onsala 20 m diameter telescope in Sweden is equipped with receivers which provide continuou​s frequency coverage in the ranges 18-50, 67-87 and 85-116 GHz with 4 GHz IF bandpass, dual polarisations and full mutual sideband rejection (<−13 dB)If the spectrometer bandwidth is reduced to 2.5 GHz  then in the two high frequency bands both sidebands can be observed simultaneously ("2SB"), with these sidebands having centres 12 GHz apart. This spectrometer setup enables e.g. such important lines as CS 2-1 near 98 GHz, and 13CO/C18O near 110 GHz, to be observed at the same time. The lower portion of the 3/4 mm band, 67-87 GHz, enables observations of low-energy or ground state transitions of some important deuterated species such as DCO+, DCN, DNC, N2D+, HDO, DC3N etc.

We welcome proposals for Large programmes, i.e. spanning more than one semester and/or require a large number of hours (>~500 h)​.​

The telescope is open for scientists from all countries.

More information about Onsala 20 m telescope proposals.


The Swedish LOFAR station at Onsala Space Observatory is an array of antennas for the frequency bands 10–90 MHz and 110–240 MHz. It is part of the International LOFAR Telescope (ILT), but is offered here in stand-alone mode.

The Swedish LOFAR station is open for scientists from all countries.

More information about Swedish LOFAR station proposals.

Proposals for Directors Discretionary Time (DDT)​

DDT proposals for observations with the APEX telescope, the Onsala Space Observatory 20 m telescope, and the Swedish LOFAR station in stand-alone mode can be submitted at any time. In general, a DDT proposal requires a special justification of why the project could not be proposed for a regular deadline. A DDT proposal should follow the same format as regular proposals, e.g., the scientific justification should be no more than two A4 pages long, plus figures and tables if needed (for a total of maximum six pages); if only a few hours of observing time are requested, the justification can be shorter. For information about telescopes, instruments, proposal preparation, etc., see links in the left column of this page.​​

All DDT proposals are to be submitted through the NorthStar system. When you have submitted the DDT proposal, please download it in pdf form from NorthStar, and send the pdf file to, and



Calls for proposals for single-dish observations with the Onsala 20 m telescope and APEX, and for stand-alone observations with the Swedish LOFAR station in Onsala, are normally issued twice per year, with deadlines in April/May and October. VLBI-observations are handled through a separate proposal procedure (not by Onsala Space Observatory).


Calls for proposals for observations with some other related instruments can be found here:

The European VLBI Network (EVN) - Using the EVN
> ALMA Science Portal at ESO
> European Southern Observatory (ESO) - Science Users Information
> Low Frequency Array (LOFAR) - Observing with LOFAR 

Note: APEX data can be accessed through the ESO Science Archive APEX Query Form.​​​​​​

Published: Tue 02 Jun 2020.