Below we acknowledge people who have contributed explicitly and implicitly to the development of X-PSI. If you wish to have your name removed, please notify the X-PSI Team. Please also prompt us to update this page if you have engaged with this project: your time is a resource we wish to acknowledge. Specific patch or feature acknowledgements are often reported in the project History (CHANGELOG). Affiliations and contact details are only listed for team members to ease maintainability.


The X-PSI team may be contacted privately at xpsi-team[at]

Project maintainers

  • Thomas E. Riley (t.e.riley[at], University of Amsterdam

Active developers

Requirement is to have added a feature to latest major version.

  • Thomas E. Riley

Experienced users

People who are experienced with the X-PSI package.

  • Devarshi Choudhury (d.choudhury[at], University of Amsterdam

Science Case developers

The grant-holding architects of past, present, and future X-PSI science.

  • Anna L. Watts (A.L.Watts[at], University of Amsterdam

Past developers

Requirement is to have added a feature to previous major version.


Contributor group one

Explicit engagement, testing (including contribution of patches explicitly or implicitly), and (optionally) direct application to their research.

  • Sebastien Guillot
  • Devarshi Choudhury
  • Anna Bilous
  • Emma van der Wateren
  • Bob de Witte

Contributor group two

Intellectual contribution & engagement (explicit and/or implicit).

  • Yuri Cavecchi
  • Geert Raaijmakers
  • The NICER collaboration
  • Alex Chen
  • Frank Chambers


Specific acknowledgements of people whose direct advice either influenced the direction of this project or led to some specific improvements.

  • CythonGSL header file
  • Existing open-source projects (which are either external dependencies or served as examples during the development of this project, such as emcee and stingray)
  • Daniela Huppenkothen (for pointing towards nested sampling algorithms and for abstract discussion of the statistical framework underlying X-PSI)
  • Will M. Farr & Ilya Mandel (for advice about posterior computation validation, and about model space definitions)
  • Will M. Farr (for ideas to accelerate likelihood function evaluation; WIP)
  • Sam Geen (for expanding support to include Windows OS)


This project is built upon the work of many researchers in many fields. For citations to (astro)physics and (astro)statistics literature, please see the technical documents pointed to in the Citation section. Moreover, we point to the bibliograpy of Riley et al. 2019 (ApJL, 887, L21) as the first published application of the X-PSI package, and to the ApJL Focus Issue of which this article is a member.


T.E.R. and A.L.W. acknowledge support from ERC Starting Grant No. 639217 CSINEUTRONSTAR and ERC Consolidator Grant No. 865768 AEONS.