AO-1 Programmes

The 1st Announcement of Opportunity (AO-1) for the PLATO Guest Observers (GO) Programme opened on 7 April 2026 and closed on 21 May 2026, covering observing windows during the first two years of the mission. A total of 117 proposals were received, comprising approximately 76,000 observing requests. All eligible proposals underwent technical review by mission experts in June and were then scientifically evaluated by the PLATO Time Allocation Committee (TAC) during its meetings in July 2026.

Based on the TAC's recommendation, ESA's Director of Science has approved the awards and waitlist listed below. In total, 23 proposals were awarded observing time and a further 28 placed on the waitlist, spanning a broad range of scientific investigations complementary to PLATO's core science objectives. The demand for the AO-1 Call corresponds to an estimated oversubscription of 2.3 to 5.1 in number of proposals, depending on the inclusion of waitlisted proposals in the final observing schedule. Final values will depend on in-orbit performance and scheduling optimisation.

All Principal Investigators (PIs) are informed of the outcome by email and receive the TAC feedback for their proposals. As with any space mission, an award or waitlist status cannot guarantee execution, as technical and operational constraints may affect the final observing programme. All teams of awarded and waitlisted proposals are therefore requested to carefully review the information regarding “Scheduling, Constraints, and Required Actions” provided below.

The PLATO team congratulates the successful proposers and thanks all applicants for their interest in the mission and in this inaugural opportunity. 

A short article highlighting the breadth and diversity of the new science programmes enabled through the AO-1 Call can be found here.

Awards

Abstracts for all awarded proposals can be found here.

Waitlist

Abstracts for all waitlisted proposals can be found here.

Scheduling, Constraints, and Required Actions
 

Publication of Targets and Processing Types: Details of the awarded and waitlisted targets will be published at a later stage, following completion of the GO Programme verification process. This stage will allow PIs to first review and correct implementation-related information provided during proposal submission, if needed. Information on final processing types will likewise be communicated later, as these may evolve during the detailed scheduling optimisation process.

Scheduling: Proposing teams are reminded that a TAC recommendation for award or waitlist status does not guarantee that observations will be scheduled. Scheduling remains contingent on PLATO's in-orbit performance and available resources. Following commissioning, and during each execution of the PLATO Target Planning Tool (currently foreseen prior to each quarterly uplink), available GO resources will first be allocated to awarded proposals and then, where resources remain, to waitlisted proposals.

Technical Constraints: Scheduling is constrained not only by telemetry, but also by other technical limitations, including processing-type budgets and detector-level capacities. The impact of these constraints may also vary between quarters. Consequently, while the TAC ranking of proposals and the PI ranking of targets will be respected wherever possible, the final schedule may not strictly follow these rankings if technical or operational constraints prevent proposals or targets from being accommodated. 

Processing Types (e.g. Centroids): Given the complexity of the technical constraints, the final processing types may need to differ from those requested. The PLATO Science Operations Centre (SOC) may contact affected teams closer to the start of observations to identify the most suitable implementation. In particular, current demand for centroid measurements may exceed available on-board resources. Where necessary, the PLATO SOC will work with PIs to identify alternative solutions that preserve the scientific objectives while remaining within mission constraints. 

Duplicate Targets: To maximise the scientific return of the mission and encourage a collaborative spirit, duplicate targets will be observed only once using the highest requested observing mode, where possible. The resulting data products will be made available simultaneously to all relevant proposing teams, who are encouraged to collaborate or to agree on independent analyses, as appropriate.

Waiving Proprietary Rights: Some proposals may wish to make their data public immediately, which requires the following aspects to be taken into account. Please contact the PLATO Helpdesk closer to the time of your observations to ensure that this preference is implemented when the data are ingested into the PLATO Archive (PAX). In the case of duplicate targets, for example where one team requires proprietary access while another wishes to make the data public immediately, the involved teams are expected to coordinate closely and ensure that the rights and needs of all parties are respected.

Action Required: PIs of awarded and waitlisted proposals are requested to verify that their target lists, including all CfP input and output files, are correct and up to date. Any issues identified should be reported promptly to the PLATO Helpdesk. Where technical reviews have already identified inconsistencies, the PLATO SOC may also contact proposers directly to request updates. Any questions during this process should likewise be directed to the PLATO Helpdesk.