CHEOPS  "Frequently Asked Questions" :  AO-1


Below is a collection of Frequently Asked Questions (FAQs), together with answers, relating to the preparation and submission of proposals for CHEOPS AO-1. The page will be updated during the call to include additional questions that come up during the period that the call is open.

If you do not find an answer to the question you have, please review the documentation provided on the AO-1 webpage. If you still cannot find the answer, then please send an email to

Please note that it may take a few days for questions to be answered, and to be put up onto this webpage.

Incase of problems with the email address noted above, please contact   kate dot isaak at esa dot int, replacing "dot" with "." and "at"  with "@".


Latest update:    25 April 2019


Q1   HOw to get a cosmos user account/ID

To submit proposals for the CHEOPS Guest Observers Programe you will need to obtain a Cosmos ID. You can use the tool at this link to check whether you already have a Cosmos ID and to request one if not.  It is recommended to do this early on.


Q2   WHy do I need to register for the CHEOPS Guest Observers Programme

Selected links from the AO-1 page are restricted to members of the CHEOPS Guest Observers Programme. This has been done to prevent spamming/excessive loading of ftp sites. Membership can be easily (and quickly) requested using the tool at this link. It is recommended to do this early on.


Q3   Applying to observe Targets that are brighter or fainter than the CHEOPS requirements

The requirements for the CHEOPS mission have been based around two sizing cases - the observation of an Earth-sized planet around G5 dwarfs with v-band magnitudes between 6 and 9, and observation of a Neptune-sized planet around a K-type dwarf equal to or brighter than v-band magnitude of 12. Performances outside these are not guaranteed. Potential observers may submit proposals for evaluation by the TAC at their own risk. Details of the implications of observing brighter and fainter targets are discussed in the Observers Manual.


Q4   Targets of Opportunity (ToO)

There is no ToO programme on CHEOPS. However, proposals to observe newly discovered targets or targets newly declared to be of high scientific interest may be submitted to the Discretionary Time Programme which is foreseen to open around the time of the In-orbit Commissioing Review, currently foreseen to take place in January 2020. A short descriptoin of the programme is included in the Policies and Procedures document that can be found on the AO-1 page. Further details will be made available shortly before the Programme opens.



Q5   Querying the reserved target list

The only way to query the reserved target list is via the tool provided at the link provided on the AO-1 webpage eg.



Q6 Observing solar system/"moving" targets

The CHEOPS attitude and control system has been designed to track objects moving at sidereal rates. As such, proposals to observe solar system objects moving at non-sidereal rates will not be accepted for AO-1. A dedicated campaign to estabilsh the capabilities of CHEOPS for observations of moving targets/solar system objects will be undertaken during the first year after launch. The results, together with any updates on the possibility to submit moving target proposals, will be communicated to the Community shortly after the campaign and analysis has been completed.