Agayeva, S.Aivazyan, VAlishov, S.Almualla, M.Andrade, C.Antier, S.Bai, J-MBaransky, A.Basa, S.Bendjoya, P.Benkhaldoun, Z.Beradze, S.Berezin, D.Bhardwaj, U.Blazek, M.Burkhonov, O.Burns, E.Caudill, S.Christensen, N.Colas, F.Coleiro, A.Corradi, W.Coughlin, M. W.Culino, T.Darson, D.Datashvili, D.de Wasseige, G.Dietrich, T.Dolon, F.Dornic, D.Dubouil, J.Ducoin, J-GDuverne, P-AEsamdin, A.Fouad, A.Guo, F.Godunova, VGokuldass, P.Guessoum, N.Gurbanov, E.Hainich, R.Hasanov, E.Hello, P.Hussenot-Desenonges, T.Inasaridze, R.Iskandar, A.Ishida, E. E. O.Ismailov, N.du Laz, T. JegouKann, D. A.Kapanadze, G.Karpov, S.Kiendrebeogo, R. W.Klotz, A.Kochiashvili, N.Kaeouach, A.Kneib, J-PKou, W.Kruiswijk, K.Lombardo, S.Lamoureux, M.Leroy, N.Su, A. Le VanMao, J.Masek, M.Midavaine, T.Moeller, A.Morris, D.Natsvlishvili, R.Navarete, F.Nissanke, S.Noonan, K.Noysena, K.Orange, N. B.Peloton, J.Pilloix, M.Pradier, T.Prouza, M.Raaijmakers, G.Rajabov, Y.Rivet, J-PRomanyuk, Y.Rousselot, L.Ruenger, F.Rupchandani, VSadibekova, T.Sasaki, N.Simon, A.Smith, K.Sokoliuk, O.Song, X.Takey, A.Tillayev, Y.Melo, I. Tosta E.Turpin, D.Postigo, A. de UgarteVardosanidze, M.Wang, X. F.Vernet, D.Vidadi, Z.Zhu, J.Zhu, Y.2022-11-072022-11-072022-11-072022-01-0110.1117/12.2630240https://infoscience.epfl.ch/handle/20.500.14299/192053WOS:000865467900041GRANDMA is a world-wide collaboration with the primary scientific goal of studying gravitational-wave sources, discovering their electromagnetic counterparts and characterizing their emission. GRANDMA involves astronomers, astrophysicists, gravitational-wave physicists, and theorists. GRANDMA is now a truly global network of telescopes, with (so far) 30 telescopes in both hemispheres. It incorporates a citizen science programme (Kilonova-Catcher) which constitutes an opportunity to spread the interest in time-domain astronomy. The telescope network is an heterogeneous set of already-existing observing facilities that operate coordinated as a single observatory. Within the network there are wide-field imagers that can observe large areas of the sky to search for optical counterparts, narrow-field instruments that do targeted searches within a predefined list of host-galaxy candidates, and larger telescopes that are devoted to characterization and follow-up of the identified counterparts. Here we present an overview of GRANDMA after the third observing run of the LIGO/VIRGO gravitational-wave observatories in 2019 - 2020 and its ongoing preparation for the forthcoming fourth observational campaign (O4). Additionally, we review the potential of GRANDMA for the discovery and follow-up of other types of astronomical transients.Engineering, AerospaceAstronomy & AstrophysicsInstruments & InstrumentationOpticsEngineeringstars: neutrongravitational waveselectromagnetic counterpartstext::conference output::conference proceedings::conference paper