4MOST - 4-metre Multi-Object Spectroscopic Telescope
4-m Multi-Object Spectroscopic Telescope

Community Surveys

During the initial 5-year period of 4MOST operations, 30% of the total available observing time will be available to the ESO community. The following provides a high-level description of the process for selecting observing programmes for this time.

4MOST was designed as a survey facility, and for a period of at least 5 years, 4MOST will be entirely dedicated to executing a comprehensive survey programme, to the exclusion of all other types of observing programmes. Furthermore, all 4MOST surveys will be ESO Public Surveys (meaning that their science case and scope need to be comprehensive enough to be of significant legacy value to the astronomical community at large). Therefore, it will not be possible to apply for time on 4MOST in response to the usual biannual Call for Proposals issued by ESO. Instead, ESO issued a single Call for Proposals for Public Surveys with 4MOST that covered the entire initial 5-year period of 4MOST operations.


Application and Selection Process

Workflow resulting in the final definition of the 4MOST Survey Programme.

The process by which the final, complete 4MOST Survey Programme will be defined is governed by ESO’s 4MOST Policies. In particular, these policies govern the application and selection procedure for Community Surveys, a process which is managed by ESO.

In brief, this process was set in motion with the 4MOST consortium publishing a set of 13 articles in the March 2019 issue of the ESO Messenger, providing extensive information on the 4MOST project, the facility, the operations scheme, the survey strategy and the Consortium Surveys. The consortium and ESO then further engaged with the community by jointly organising a workshop, entitled Preparing for 4MOST: A community workshop introducing ESO’s next-generation spectroscopic survey facility, which was held in Garching in May 2019. This workshop again provided interested members of the community with information about 4MOST, as well as with an opportunity to ask questions and discuss ideas and tentative plans for surveys. The workshop’s programme provides links to the videos and PDFs of the presentations. A summary of the workshop is provided by Liske & Mainieri (2019).

Following this period of information dissemination, ESO issued a Call for Letters of Intent (LoI) for public spectroscopic surveys with 4MOST in November 2019, with a submission deadline on 28 February 2020. The LoIs were reviewed by ESO’s Public Survey Panel (PSP), and the successful teams were invited to submit a detailed proposal by 15 December 2020. ESO and the 4MOST consortium then supported the preparation of proposals by organising a 2nd 4MOST community workshop, entitled Planning for 4MOST: toward the 4MOST survey programme, in July 2020, and by providing access to the 4MOST Facility Simulator. After evaluating the feasibility of different combinations of proposed surveys, the PSP is now reviewing all proposals and will issue a recommendation. Based on this recommendation, the survey plan for the combined recommended Community and Consortium Surveys will be optimised and its implications in terms of predicted success and efficiency analysed. The resulting report and the PSP recommendation will form the basis for the recommendation of ESO’s Observing Programmes Committee (OPC) for the final 4MOST survey programme.

Full details of the application and selection procedure for Community Surveys are provided by ESO’s 4MOST Policies.


Participating vs. Non-Participating Surveys

Proposers had the choice of whether to propose a Participating or a Non-Participating Community Survey. Participating Surveys will join the Consortium Surveys in the 4MOST Science Team immediately after their selection. All Participating Surveys will be planned and executed jointly as a single science programme. Importantly, each survey will only be “charged” the observing time for the actual fibres used by them (including fractional overheads and any residual inefficiencies). Depending on a survey’s observing requirements and target density, this parallel observing mode may be extremely efficient. In contrast, Non-Participating Surveys will be executed on their own on named nights or half-nights, and “charged” observing time accordingly, regardless of how many fibres they actually used. It should be remembered in this context that 4MOST will feature both a high-resolution as well as two low-resolution spectrographs, fed by one third and two thirds of the fibres, respectively. Efficient use of 4MOST thus requires a sufficient density of both high-resolution and low-resolution targets separately.

The description of the operations model provides further details on the differences between Participating and Non-Participating Surveys.

As mentioned above, Participating Community Surveys will join the 4MOST Science Team. As such they will be subject to the Science Team Policies, which govern all aspects of the scientific collaboration, including team membership, data access and sharing, scientific exploitation, and publication. These policies are meant to embody a spirit of scientific partnership which recognizes the value of cooperation across survey boundaries to the extent that it strives to minimize these boundaries as far as possible, while at the same time respecting the effort invested towards attaining a survey’s main science goals and protecting these.


Other Considerations

Proposed surveys will need to fit within the total amount of observing time available for Community Surveys, estimated as 0.96 million fibre-hours per year for the low-resolution spectrographs, and 0.48 million fibre-hours per year for the high-resolution spectrograph.

When selecting Participating Community Surveys the PSP will give some consideration to their compatibility with the Consortium Surveys and with each other in terms of observing requirements. No such constraints will apply to Non-Participating Surveys, but in terms of feasibility (e.g. RA and dark time pressure) they will of course be tensioned against other Community and Consortium proposals in the usual way.

The Science Team Policies stipulate some restrictions regarding the overlap between the target list of a Participating Community Survey and those of the Consortium Surveys. The number of targets that a Participating Community Survey has in common with a Consortium Survey shall not exceed 20% of the number of the Consortium Survey’s targets, and the number of targets in common with all Consortium Surveys shall not exceed 20% of the number of the Participating Community Survey’s targets. Similarly, ESO’s 4MOST Policies specify that Non-Participating Community Surveys shall not have more than 30% of their targets in common with those of the Consortium Surveys.


Summary of Available Information

Coming soon:

  • Continuously updated Survey Plan