FAQ

The TAC evaluates proposals primarily on scientific merit, taking into account all applicable constraints, including the justification for PLATO and the efficient use of telescope resources. Reviewers may therefore consider technical details such as target-level observing modes and cumulative telemetry requirements. Individual reviewers assign grades and comments, which are then discussed during panel meetings where assessments are consolidated. After these meetings, renormalisations per panel are considered, and a single ranked list of proposals is generated. The TAC Chair and Panel Chairs jointly review this list, considering reviewer comments, cumulative telemetry needs, and the overall balance across science categories. Adjustments may be made to ensure appropriate representation.

There are no fixed numerical rules, meaning the TAC is not bound to prioritise proposals based on category or telemetry quotas. This flexibility is intentional for the inaugural AO Call, allowing recognition of high-impact proposals even if they require larger telemetry resources or fall within less‑subscribed categories. Both large and focused programmes may be equally compelling. Final decisions are based on informed scientific discussion rather than preset criteria.

The TAC may recommend partial acceptance of a proposal. For instance, if the science case is strong but does not depend on the full target sample, the TAC may recommend allocating time to only a subset of the proposed targets.

Proposers are responsible for ensuring their original submission contains a single, complete, well‑justified target list that is integral to their project. Proposals are not expected to highlight pre‑prioritised subsets to the TAC, as this would imply that the proposal considers only part of the sample to be essential. However, proposers may order their target lists according to their priorities (see below).

If only part of the requested telemetry can be granted, the SOC will use this sequence as a first‑order guide when selecting targets, while optimising within available telemetry. This optimisation may require skipping certain targets (e.g., high‑telemetry or time‑critical ones) in favour of more feasible options. Due to resource constraints and the complexity of science operations, iterative exchanges between the TAC, SOC, and proposers are generally not feasible. Therefore, the initial submission must be sufficiently complete to allow SOC to perform any required optimisation.

Team expertise is visible only to ESA and is reviewed solely to confirm that the proposing team has the resources necessary to make effective use of the observations. The TAC evaluates proposals purely on scientific merit and does not receive any non‑anonymous information. In cases where the TAC needs verification of specific claims in the science case (e.g., access to proprietary observing time), ESA may anonymously confirm these claims without revealing team identities. This process supports fair evaluation while enabling necessary factual checks.

Proposers and reviewers remain fully anonymous throughout the evaluation process. Limited personal information is disclosed only after the Director of Science issues the final awards. At that point, the principal investigators’ surnames, affiliations, and countries of affiliation for successful proposals are published on the PLATO website. Reviewers who later choose to conclude their service may list their TAC role in their CVs or professional profiles.

In some cases, the TAC may recommend awarding observing time to multiple proposals with overlapping target lists. When this occurs, the TAC may provide specific guidance. Typically, teams are put in contact to decide whether to collaborate, coordinate, or continue independently. In all cases, each team retains the standard proprietary period for their data. In exceptional circumstances (for example, if a team voluntarily waives its proprietary rights), the TAC may recommend awarding time under explicit conditions.

PLATO has different configuration modes for N‑CAMs and F‑CAMs, and targets are configured for each independently. Due to these constraints, a target may be observed by F‑CAMs but not by N‑CAMs, or vice versa. This can occur even in the centre of the field of view where 26 cameras overlap. However, once a target is configured for N‑CAM observations, it will be observed with all N‑CAMs in which it is visible. This is verified using full‑frame images taken in flight to ensure the target lies on functioning pixels.

No. Due to the technical constraints described above, it is not possible to restrict N‑CAM usage to save telemetry.

No. Proposers may only request existing operating modes. New observing modes cannot be implemented.

During nominal science operations, PLATO will acquire full‑frame images for all cameras at the beginning and end of each quarter as part of calibration. These calibration data may be released together with the L0 and L1 data, although the exact schedule is not yet finalised. Calibration data are generally released after validation, whose timing depends on in‑orbit performance and available resources. Validation is expected to take longer early in the mission and may become faster as operations stabilise.

Targets of Opportunity (ToOs) are accommodated on a best‑effort basis, as they introduce significant technical and scheduling constraints into observation planning. Because of these complexities, it is not possible to define in advance which ToOs can be scheduled or which existing targets may need to be displaced. Only strongly justified ToOs that receive high rankings from the TAC will be considered and, if approved, integrated on a case‑by‑case basis.