| Participant No* | Participant organisation name | Country |
| 1 (Coordinator) | Istituto Nazionale di Astrofisica (INAF) | Italy |
| 2 | Space Research Organization
Netherlands (NWO-I/SRON) |
The Netherlands |
| 3 | Max-Planck-Gesellschaft (MPG) | Germany |
| 4 | National Observatory of Athens (NOA) | Greece |
| 5 | University of Leicester (ULEIC) | United Kingdom |
| 6 | Universidad de Alicante (UA) | Spain |
| 7 | European Gravitational Observatory (EGO) | Italy |
| 8 | Istituto Nazionale di Fisica Nucleare (INFN) | Italy |
| 9 | Centre National de la Recherche Scientifique (CNRS) | France |
| 10 | Gran Sasso Science Institute (GSSI) | Italy |
| 11 | Universitè de Genève (UNIGENEVE) | Switzerland |
| 12 | Agencia Estatal Consejo Superior de
Investigaciones Cientificas (CSIC) |
Spain |
| 13 | Commissariat à l’énergie atomique et
aux énergies alternatives (CEA) |
France |
| 14 | Consiglio Nazionale delle Ricerche (CNR) | Italy |
| 15 | Thales Alenia Space Italia SPA (TAS) | Italy |
| 16 | University College Dublin (NUID UCD) | Ireland |
| 17 | Université de Liège (ULIEGE) | Belgium |
| 18 | Università degli Studi di Ferrara (UNIFE) | Italy |
| 19 | Università degli Studi di Palermo (UNIPA) | Italy |
| 20 | Ceske Vysoke Uceni Technicke V Praze (CVUT) | Czech Republic |
| 21 | Centrum Astronomiczne Im. Mikolaja
Kopernika Polskiej Akademii Nauk (NCAC) |
Poland |
| 22 | Leiden University (ULEIDEN) | The Netherlands |
| 23 | Physikalisch-Technische Bundesanstalt (PTB) | Germany |
| 24 | Università degli Studi di Genova (UNIGE) | Italy |
| 25 | Eberhard Karls Universität Tübingen (EKUT) | Germany |
| 26 | Ludwig-Maximilians-Universität München (LMU MÜNCHEN) | Germany |
| 27 | Associação do Instituto Superior Técnico para a Investigação e Desenvolvimento (IST-ID) | Portugal |
| 28 | Universiteit van Amsterdam (UvA) | The Netherlands |
| 29 | Swhard srl (SWHARD) | Italy |
| 30 | Johannes Gutenberg-Universität Mainz (UMAINZ) | Germany |
| 31 | Tartu Ülikool (UTARTU) | Estonia |
| 32 | Laboratório de Instrumentação e Física Experimental de Partículas (LIP) | Portugal |
| 33 | Danmarks Tekniske Universitet (DTU) | Denmark |
| 34 | Eötvös Loránd Tudományegyetem (ELTE) | Hungary |
| 35 | University of Bath (UBATH) | United Kingdom |
| 36 | Stiftung Deutsches Elektronen-Synchrotron (DESY) | Germany |
| 37 | Kaon GmbH (KAON) | Germany |
| 38 | COSINE Research BV (CR) | The Netherlands |
