The browser you are using is not supported by this website. All versions of Internet Explorer are no longer supported, either by us or Microsoft (read more here:

Please use a modern browser to fully experience our website, such as the newest versions of Edge, Chrome, Firefox or Safari etc.

Picture of Abbas Askar

Abbas Askar


Picture of Abbas Askar

COCOA Code for Creating Mock Observations of Star Cluster Models


  • Abbas Askar
  • Mirek Giersz
  • Wojciech Pych
  • Emanuele Dalessandro

Summary, in English

We introduce and present results from the cocoa (Cluster simulatiOn Comparison with ObservAtions) code that has been developed to create idealized mock photometric observations using results from numerical simulations of star cluster evolution. cocoa is able to present the output of realistic numerical simulations of star clusters carried out using Monte Carlo or N-body codes in a way that is useful for direct comparison with photometric observations. In this paper, we describe the cocoa code and demonstrate its different applications by utilizing globular cluster (GC) models simulated with the mocca (MOnte Carlo Cluster simulAtor) code. cocoa is used to synthetically observe these different GC models with optical telescopes, perform point spread function photometry, and subsequently produce observed colour–magnitude diagrams. We also use cocoa to compare the results from synthetic observations of a cluster model that has the same age and metallicity as the Galactic GC NGC 2808 with observations of the same cluster carried out with a 2.2 m optical telescope. We find that cocoa can effectively simulate realistic observations and recover photometric data. cocoa has numerous scientific applications that maybe be helpful for both theoreticians and observers that work on star clusters. Plans for further improving and developing the code are also discussed in this paper.

Publishing year





Monthly Notices of the Royal Astronomical Society

Document type

Journal article


Oxford University Press


  • Astronomy, Astrophysics and Cosmology




  • ISSN: 1365-2966