CHEOPS Discretionary programme


Last update 4 April 2022

This webpage provides prospective users of CHEOPS with all information (policies and procedures for the programme, documentation, tools and links)  required to prepare and submit proposals to the CHEOPS Discretionary Pragmme, through which 5% of the nominal science observing observing time on CHEOPS will be allocated.

To be eligible for the Discretionary Programme a proposal must meet the following criteria:

  • Contain a single target of high scientific interest
  • Demonstrate that the target was either (a) discovered, or (b) declared to be of high scientific interest since the close of the previous call (15 March 2022)
  • Contain a target/event that is observable by the date by theend of the nominal mission  (24 Septemeber 2023), and that is not on the CHEOPS Reserverd Target List
  • It is noted that the requirement to be either newly discovered or newly determined tobe of high scientific interest since the close of AO-3 (i.e  15 March 2022) is waived for proposals led by PhD students (as part of their PhD work) and/or early career researchers within 2 years of the award of their PhD.

Details regarding what needs to be included in a proposal, together with the tools and documentation to support proposal preparation and submission, can be found in the Policies and Procedures document for the Discretionary Programme. Prospective observers are STRONGLY RECOMMENDED to read very carefully through this document before starting work on any proposal. 


Important Notes:

  • The sole way to submit proposals for the CHEOPS Discretionary Programme is through the Phase I Proposal Handling Tool. To submit a proposal you will need to have user credentials for the Cosmos Website AND to be a member of the CHEOPS Guest Observers Programme Group. You will also need to be a member of the GO Programme group to be able to download the software for the Scheduling Feasibility Checker, which is one of the tools that you will need to prepare your proposal. Requests for both IDs and group membership are made by following the instructions at the following link:
  • The reserved target list must be checked to confirm that a target is not already reserved by other programmes (link to checker provided below).  All targets in AO-3 proposals are reserved until the list of successful AO-3 proposals is published, foreseen by end of May 2022. Potential AO-3 targets are not yet included on the reserved target list and thus are not visible to the reserved target list checker. Until end of May 2022, prospective observers must contact the CHEOPS project scientist (via,  or kate dot isaak at, replacing the " dot " by "." and " at " by "@".) to check whether their target was submitted in an AO-3 proposal. Once AO-3 observing time has been awarded the reserved target list will be updated to include all targets for which CHEOPS observing time is to be scherduled by the end of the nominal mission.
  • It is important to appreciate that the majority of CHEOPS observations will be time-critical. These can be difficult to schedule, and in some cases may not be possible even if a target is awarded observing time and is high priority.
  • CHEOPS is a small mission, with a correspondingly small team supporting the Community in their use of CHEOPS. Response times to questions may therefore take a little longer than may be the case for a larger mission/observatory.
  • Notifications of updates/changes to application procedures wlll be published on the page at this link - people thinking about applying for discretionary time are advised to check this page regularly and certainly before submitting their proposals.
  • A list of proposals awarded time in the discretionary programme is available at this link.
  • Please check the Frequently Asked Questions page for answers to commonly asked questions

In case of questions, please send an email to,  or kate dot isaak at, replacing the " dot " by "." and " at " by "@".


Key Documentation:


A number of tools, documents, presentations and links are available to help you with your proposal preparation and submission.

Tools and supporting manuals:

Useful presentations, reference data and links    

User-contributed tools/aids:

Below are links to tools that have been developed by members of the CHEOPS Science Team and the CHEOPS Consortium to aid preparing and analysing CHEOPS observations. These are shared for use at the user's own risk, with caveats and warnings that are detailed in the individual documents.



Please check the Frequently Asked Questions page for common questions as well as details of who to contact in case your question is not answered on the page.