The AO-1 Call is closed.
You can find all approved programmes here.


Outcome of the AO-1 Call

The CHEOPS Time Allocation Committee (TAC) met on 2-3 July 2019. Details of proposals awarded time by the Director of Science, based on the recommendations of the TAC, can be found at

The next opportunity to apply for observing time on CHEOPS will be when the Discretionary Time Programme opens, currently foreseen aroud the time of the start of routine operations/early 2020. Details will be posted on the CHEOPS Guest Observers webpages when available. 


First Announcement of Opportunity (AO-1) for participation in the CHEOPS Guest Observers Programme

This announcement solicits proposals for observations to be carried out as part of the CHEOPS Guest Observers Programm,  and covering the period of February 2020 to January 2021.



Release of AO-1: call for Phase I observing proposals           19 March 2019

Deadline for submission of Phase I observing proposals        16 May 2019 (14:00 CEST)

Meeting of the CHEOPS Time Allocation Committee              2 - 4 July 2019

Announcement of award of observing time on CHEOPS         End July 2019

Preparation of Phase II inputs                                            14 August - 10 Sept 2019

CHEOPS launch slot                                                           15 October - 14 November 2019

Reference start date for CHEOPS nominal operations            1 February 2020


Important Notes:

Prospective observers are requested to take note of the following points:

  • All proposals must be submitted via the Phase I Proposal Handling Tool. Submission requires the use of a Cosmos Website ID together with membership of the CHEOPS Guest Observers Programme Group. Registration is required to download the software for the Scheduling Feasibility Checker, which is one of the tools needed to prepare proposals (see notes below) and also to download simulated CHEOPS data. Requests for both IDs and group membership need to be made by following the instructions at the following link:

         We recommend that you get an ID/register early during the call.

  • A minimum of 1 orbit per target, and a maximum of 100 orbits may be requested per proposal.
  • It is important to appreciate that, due to the nature of the science that CHEOPS will address, the majority of CHEOPS observations will be time critical. These can be difficult to schedule, and in some cases it may not be possible even if a target is awarded observing time and is high priority.
  • All tools and documentation, with the exception of ESA Phase I Proposal Handling Tool are provided by the CHEOPS Consortium, and are the same as those used by the Science Team to prepare the Guaranteed Time Observing Programme.
  • Simultaneous scheduling of CHEOPS observations with other facilities will not be possible.
  • CHEOPS is a small mission, with a correspondingly small team to support Guest Observers. Observers are advised to not to leave proposal preparation to the last weeks, as the response time incase of questions may be up to a few days.
  • Notifications of any issues/updates to Call material will be published on the page at this link - prospectiver proposers are recommended to check this page regularly during the period of the call.  ** UPDATED 29 April 2019 **




Tools and supporting manuals:

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

*** Please note: May 2020: a new virtual image of the scheduling feasibility checker has been issued in preparation for the discretionary programme (cheopsfcvm06). More details on this can be found at the links above. Note that the installation instructions and guidelines are relevant to the NEW image. ***



Useful Data/information:


User-contributed tools/aids:

Here we provide links to documentation that has been deveolped by members of the CHEOPS Science Team. These are shared for use at the user's own risk, with caveats and warnings that are detailed in the individual documents.