Observing with CHEOPS

CHEOPS' science programme consists of two major components: The Guest Observers (GO) and Guaranteed Time Observers (GTO) Programmes.


CHEOPS Guest Observers (GO) Programme

In CHEOPS' nominal mission, 20% of science observing time is made available to the scientific community to conduct investigations of their choice in the form of an ESA-run Guest Observers’ (GO) Programme. Proposals for GO Programme observing time are mainly solicited through a series of annual Announcements of Opportunity (AOs). Additionally, to allow new targets to be included in the GO programme at any time during the mission, up to 25% of the open time are allocated as Discretionary Time (DT), as part of the Discretionary Programme (DP). This will be overseen by ESA, in consultation with the chair of the ESA-appointed time allocation committee (TAC) and the CHEOPS Principal Investigator (PI).

On this website we provide the links to key information relevant to prospective users of CHEOPS.

Questions on the Guest Observers Programme? Please send an email to cheops-support at cosmos.esa.int.


Guaranteed time Observing (GTO) Programme

In CHEOPS' nominal mission, 80% of the science observing time is dedicated to the CHEOPS Guaranteed Time Observing (GTO) Programme. The definition of the GTO programme is under the responsibility of the CHEOPS Science Team, which is chaired by David Ehrenreich (previously Didier Queloz). Details of membership of the Science Team can be found at this link. An overview of the GTO programme as it stands/stood at the time of the opening of the various AOs are available here:

- at the time of opening of AO-1 at this link.

- at the time of opening of AO-2 at this link.

- at the time of opening of AO-3 at this link.


Last updated 1 Mar 2023