THIRD Announcement of Opportunity (AO-3) for participation in the CHEOPS Guest Observers Programme - TO OPEN 15 FEBRUARY 2022


The third annual announcement (AO-3) for participation in the CHEOPS Guest Observers Programme was foreseen to come out on 9 November 2021. The AO was postponed and will open 15 February 2022. Full details of the timeline of the call will be posted on this webpage when available. This Call will be the final annual call for the nominal mission, and as such will cover observing time from approximately late June 2022 to late September 2023. Details of how to apply, including all tools and relevant documentation, will be available from this webpage.  AO-3 will follow a very similar process to that of AO-2, so to see how a typical AO runs please go to the webpage for AO-2 which can be found here.

Last updated: 13 January 2022

At this point in time it is possible to apply for observing time on CHEOPS through the Discretionary Programme. Details on the Programme, and how to apply, can be found here.

In the meantime, there are several documents, tools and webpages that are available to help you to determine already now whether the capabilities of CHEOPS are appropriate for your science. These include:

  1. An overview of the photometric precision of CHEOPS, including summaries of the photometric precision that has been achieved in-orbit over the design magnitude range of CHEOPS of Gmag 6 - 12 ( (a) and (b)) as well as beyond.
  2. The exposure time calculator (ETC), designed to show the photometric precision that can be achieved with CHEOPS in observations of a star of a user-specified magnitude and spectral type in a specified integration time.
  3. An overview of the CHEOPS sky, including a summary of the pointing constraints of CHEOPS as well as good approprimation of which parts of the sky can be observed with CHEOPS.
  4. The scheduling feasibility checker (SFC), designed to enable yiou to check in detail whether your target is visibile with CHEOPS, and what the impact of interruptions in observing that result from CHEOPS' orbit. (You will need cosmos credentials to download this tool - details on how to get these are provided on the scheduling feasibility checker webpage).
  5.  The latest version of the CHEOPS Observers Manual, which includes a detailed overview of the mission, operations and payload capabilities, as well as important information on the CHEOPS data reduction pipeline and data products.
  6.  Tips for things to consider when deciding how much observing time to request and how to plan your observations.

To get a feeling for the CHEOPS data that is available, it is recommended that you take a look at the cheops data webpage, on which details of some of the first public data from CHEOPS are given.

**All observations taken by CHEOPS that are no longer subject to a proprietary period and are public can be downloaded from the CHEOPS mission archive which can be reached via this link.**

An open-source software package called pycheops has been developed by members of the CHEOPS Sciencer Team to detrend and analyse CHEOPS data. The software package (including documentation) is available "as-is" from GitHub at this link. A full description of the algorithms and assumptions used in pycheops can be found in Maxted et al. 2021 ( arxiv:2111.08828).

A list of CHEOPS papers can be found at this link. These include the definitive mission paper, key aspects of expected performance (the data reduction pipeline, the on-ground calibration campaign and the CHEOPS simulator) as well as the latest papers on CHEOPS science.

It is important to remember that a significant number of targets are reserved by the CHEOPS Science Team as part of their Guaranteed Time observing Programme which takes up 80% of the available science observing time. Reserved targets cannot be proposed for observation as part of any Guest Observers proposal. The up-to-date list of the reserved targets, which includes those that are part of active programmes from the Guest Observers Programme, will be made available at the time the call opens. Until then, a target-by-target check can be made using the so-called Reserved Target List checker tool.