

We welcome proposals for observing projects on a number of different telescopes.
Calls for proposals
APEX
Calls for proposals for single-dish observations with APEX are normally issued twice per year, with deadlines in April/May and October/November. Read more about APEX proposals.
Onsala 20-m telescope
Calls 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).
Other telescopes
Calls for proposals for observations with some other related instruments can be found here:
About the current call for proposals
APEX
Proposals are invited for observations with the APEX telescope in 2023. For complete information, see our APEX proposals page.
Deadline: Friday 17 February 2023 (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.
Other telescopes
Onsala 20 m telescope: Calls for proposals for the 20 m telescope are issued only once per year, in the autumn. Before submitting the proposal, the authors must contact the telescope scientist Henrik Olofsson to arrange with a local collaborator to support the observations.
APEX: A call for proposals for observations with APEX in 2023 will be issued in January 2023, with deadline 17 February 2023.
LOFAR single station: There are no calls for proposals for single station observations with the Swedish LOFAR station in Onsala.
DDT: Proposals for Directors Discretionary Time (DDT) can be submitted at any time (for observations with APEX, the Onsala 20 m telescope and LOFAR single station).
For EVN Call for Proposals, see the Astro VLBI page.
For APEX, calls for proposals are issued only once per year, in January.
For LOFAR proposals, see ASTRON's page on observing with LOFAR.
For proposals for Directors Discretionary Time (DDT), see below.
Observations with the Onsala 20 m telescope
The Onsala 20 m diameter telescope in Sweden is equipped with receivers which provide continuous 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 requiring a large number of hours (>~500 h).
Note: Before submitting the proposal, the authors must contact the telescope scientist Henrik Olofsson (henrik.olofsson@chalmers.se) to arrange with a local collaborator to support the observations. .
APEX
APEX, the Atacama Pathfinder EXperiment, is a 12 m diameter submillimetre telescope at 5100 m altitude on Llano Chajnantor in Chile.
The receivers currently used on Swedish time 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). Bolometer arrays are not available.
Proposals for Swedish time on APEX must have a PI with a Swedish affiliation.
For complete information, see our APEX proposals page.
Note: APEX data can be accessed through the ESO Science Archive APEX Query Form.
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 john.conway@chalmers.se, magnus.thomasson@chalmers.se and michael.olberg@chalmers.se.