Call for proposals

Observati​ons with APEX 

(For EVN Call for Proposals, see the Astro VLBI page. For LOFAR proposals, see Observing with LOFAR at Astron. For the Onsala 20 m telescope, the next deadline will be in the autumn of 2022. For proposals for Directors Discretionary Time (DDT), see below.)

Proposals are invited for observations with the APEX​ telescope in the observing period July–October 2022.

Deadline: Friday 13 May 2022 (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.

Note: ​
- APEX: Large programme proposals not are accepted.
- Onsala 20 m telescopeCalls for proposals for the 20 m telescope are issued only once per yearin the autumn, but the posibility to submit ​proposals for Directors Discretionary Time (DDT)​ at any time remains. Proposals for the 20 m telescope must have at least one co-I with a Chalmers affiliation.​​ Most projects will be observed in service mode by local staff.
LOFAR single stationFrom 2020 onwards, there will be no calls for proposals for single station observations with the Swedish LOFAR station in Onsala. Proposals for Directors Discretionary Time (DDT)​ ​can be submitted at any time.


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 (SEPIA180: 159-211 GHz; SEPIA345: 272-376 GHz; SEPIA660: 578-738 GHz) and nFLASH (nFLASH230: 200-270 GHz; nFLASH460: 385-500 GHz), and the bolometer arrays ArTeMiS (350 and 450 μm) and CONCERTO (with a Martin-Puplett interferometer for a spectral resolution of >1.5 GHz in the 130-310 GHz range).

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 telescope

Note: The next deadline for regular proposals will be in the autumn of 2022. Proposals for Directors Discretionary Time (DDT) can be submitted at any time. 
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. We welcome proposals for Large programmes, i.e. spanning more than one semester and/or require a large number of hours (>~500 h)​.​

Note: Proposals for the Onsala 20 m telescope must have at least one co-I with a Chalmers affiliation.

More information about Onsala 20 m telescope proposals​.

Proposals for Directors Discretionary Time (DDT)​

DDT proposals for observations with the APEX telescope, the Onsala Space Observatory 20 m telescope, and single station observations with the Swedish LOFAR station in Onsala 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 APEX are normally issued twice per year, with deadlines in April/May and October/November, and for the Onsala 20 m telescope once per year, with deadline in October/November. 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.​​​​​​​​​​​​​​​​​​

Page manager Published: Wed 13 Apr 2022.