Visibility Checks


CHEOPS can observe different parts of the sky at different times throughout the year (see Sky Visibility). The very first step when considering new targets for your proposal should be to familiarise yourself with the annual and monthly visibility maps, and get a feeling for which targets are within reach.

For proposals in Phase 1, observers must then use either of two tools to prove if and when their target is observable:


(Python script & Jupyter notebook)

(now installable via Docker)



Both tools allow you to check whether and when a target is visible to the instrument. You can also assess the impact that interruptions due to the satellite's passage through the South Atlantic Anomaly and Earth Occultations have on the target visibility. This serves to estimate the observing efficiency for your target, which is the fraction of time the instrument can collect photons from the target averaged over the observing window.

Note that for awarded proposals that need to draft their observation requests in Phase 2, observers are still asked to consult the Scheduling Feasibility Checker (SFC). However, the tool has been significantly modernised and is now easier to install and faster to run. If you reach Phase 2 and experience any hurdles with the SFC at that time, please do get in touch and the team will do their best to support you.


Questions about CHEOPS or the GO Programme? Please email cheops-support at and we will be happy to help!
This website was last updated on 12 March 2024.