Ready for O4 II: GRANDMA observations of Swift GRBs over eight weeks in spring 2022

¹ Department of Physics and Astronomy, University of Catania, 95125 Catania, Italy
e-mail: iara.tosta.melo@dfa.unict.it
² Sorbonne Université, CNRS, UMR 7095, Institut d’Astrophysique de Paris, 98 bis bd Arago, 75014 Paris, France
e-mail: ducoin@iap.fr
³ N. Tusi Shamakhy Astrophysical Observatory Azerbaijan National Academy of Sciences, settl.Y. Mammadaliyev, 5626 Shamakhy, AZ, Azerbaijan
⁴ School of Physics and Astronomy, University of Minnesota, Minneapolis, MI 55455, USA
⁵ Brown University, Providence, RI 02912, USA
⁶ Oukaimeden Observatory, High Energy Physics and Astrophysics Laboratory, FSSM, Cadi Ayyad University Av. Prince My Abdellah, 2390 Marrakesh, BP, Morocco
⁷ Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire J.-L. Lagrange, Boulevard de l’Observatoire, 06304 Nice, France
⁸ OCA, 14 rue Saint-Hubert, 60560 Orry-la-Ville, France
⁹ E. Kharadze Georgian National Astrophysical Observatory, Mt.Kanobili, Abastumani, 0301 Adigeni, Georgia
¹⁰ Samtskhe-Javakheti State University, Rustaveli Str. 113, Akhaltsikhe, 0080 Georgia
¹¹ Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Artemis, Boulevard de l’Observatoire, 06304 Nice, France
¹² Yunnan Observatories, Chinese Academy of Sciences, Kunming, 650011 Yunnan Province, PR China
¹³ Astronomical Observatory Taras Shevshenko National University of Kyiv, Observatorna str. 3, Kyiv, 04053 Ukraine
¹⁴ Silesian University of Technology, Faculty of Automatic Control, Electronics and Computer Science, Akademicka 16, 44-100 Gliwice, Poland
¹⁵ Astrophysique Relativiste Théories Expériences Métrologie Instrumentation Signaux, Nice, France
¹⁶ GRAPPA, Anton Pannekoek Institute for Astronomy and Institute of High-Energy Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
¹⁷ FZU – Institute of Physics of the Czech Academy of Sciences, Na Slovance 1999/2, 182 21 Praha, Czech Republic
¹⁸ Vereniging or Sterrenkunde, Balen-Neetlaan 18A, 2400 Mol, Belgium
¹⁹ Ulugh Beg Astronomical Institute, Uzbekistan Academy of Sciences, Astronomy str. 33, Tashkent, 100052 Uzbekistan
²⁰ Centre for Astrophysics and Supercomputing, Swinburne University of Technology, ARC Centre of Excellence for Gravitational Wave Discovery 685 (OzGrav), Hawthorn, Victoria, 3122 Australia
²¹ Laboratório Nacional de Astrofísica, R. dos Estados Unidos, 154 – Nações, Itajubá, MG, 37504-364 Brazil
²² Institut Universitaire de France, Ministère de l’Enseignement Supérieur et de la Recherche, 75231 Paris, France
²³ CPPM, Aix-Marseille Univ., CNRS/IN2P3, CPPM, Marseille, France
²⁴ Université Paris Cité, CNRS, Astroparticule et Cosmologie, 75013 Paris, France
²⁵ National University of Uzbekistan, 4 University str., Tashkent, 100174 Uzbekistan
²⁶ Artemis, Boulevard de l’Observatoire, 06304 Nice, France
²⁷ National Research Institute of Astronomy and Geophysics (NRIAG), 1 El-marsad St., 11421 Helwan, Cairo, Egypt
²⁸ KNC, AAVSO, Hidden Valley Observatory(H), Colfax, WI.; iTelescope, NMS, Mayhill NM, USA
²⁹ Department of Physics, University of Western Australia, Crawley, WA, 6009 Australia
³⁰ Australia ARC Centre of Excellence for Gravitational Wave Discovery (OzGrav), Australia
³¹ Physics Department and Astronomy Department, Tsinghua University, Beijing, 100084 PR China
³² Department of Aerospace, Physics, and Space Sciences, Florida Institute of Technology, Melbourne, FL, 32901 USA
³³ American University of Sharjah, Physics Department, PO Box 26666 Sharjah, UAE
³⁴ Institut für Physik und Astronomie, Universität Potsdam, Karl-Liebknecht-Str. 24/25, 14476 Potsdam, Germany
³⁵ IJCLab, Université Paris-Saclay, CNRS/IN2P3, Orsay, France
³⁶ Xinjiang Astronomical Observatory, Chinese Academy of Sciences, Urumqi, Xinjiang, 830011 PR China
³⁷ School of Astronomy and Space Science, University of Chinese Academy of Sciences, Beijing, 100049 PR China
³⁸ Oukaimeden Observatory HAO Telescope, Oukaimeden, Morocco
³⁹ Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA, 91125 USA
⁴⁰ Hessian Research Cluster ELEMENTS, Giersch Science Center, Max-n-Laue-Straße 12, Goethe University Frankfurt, Campus Riedberg, 60438 Frankfurt am Main, Germany
⁴¹ CEICO, Institute of Physics of the Czech Academy of Sciences, Na Slovance 1999/2, 182 21 Praha, Czech Republic
⁴² Laboratoire de Physique et de Chimie de l’Environnement, Université Joseph Ki-Zerbo, Ouagadougou, Burkina Faso
⁴³ IRAP, Université de Toulouse, CNRS, UPS, 14 Avenue Édouard Belin, 31400 Toulouse, France
⁴⁴ Université Paul-Sabatier Toulouse III, Université de Toulouse, 118 route de Narbonne, 31400 Toulouse, France
⁴⁵ K26 / Contern Observatory (private obs.), 1, beim Schmilberbour, 5316 Contern, Luxembourg
⁴⁶ Centre for Cosmology, Particle Physics and Phenomenology – CP3, Universite Catholique de Louvain, 1348 Louvain-la-Neuve, Belgium
⁴⁷ Physics Department and Astronomy Department, Tsinghua University Beijing, 100084, PR China; Beijing Planetarium, Beijing Academy of Science and Technology, Beijing, 100044 PR China
⁴⁸ Key Laboratory for the Structure and Elution of Celestial Objects, Chinese Academy of Sciences, 650011 Kunming, PR China
⁴⁹ Observatoire du Crous des Gats, 31550 Cintegabelle, France
⁵⁰ Société Astronomique de France, 3 rue Beethoven, 75016 Paris, France
⁵¹ University of the Virgin Islands, United States Virgin Islands, Islands, 00802 USA
⁵² SOAR Telescope/NSF’s NOIRLab, Avda Juan Cisternas 1500, La Serena, Chile
⁵³ Thüringer Landessternwarte Tautenburg, 07778 Tautenburg, Germany
⁵⁴ National Astronomical Research Institute of Thailand (Public Organization), 260, Moo 4, T. Donkaew, A. Mae Rim, Chiang Mai, 50180 Thailand
⁵⁵ Hankasalmi Observatory, Jyvaskylan Sirius ry, Verkkoniementie 30, 40950 Muurame, Finland
⁵⁶ OrangeWave Innovative Science, LLC, Moncks Corner, SC, 29461 USA
⁵⁷ Artemis, Observatoire de la Côte d’Azur, Université Côte d’Azur, Boulevard de l’Observatoire, 06304 Nice, France
⁵⁸ Silesian University of Technology, Department of Electronics, Electrical Engineering and Microelectronics, Akademicka 16, 44-100 Gliwice, Poland
⁵⁹ Université de Strasbourg, CNRS, IPHC UMR 7178, 67000 Strasbourg, France
⁶⁰ Astronomical Observatory of Taras Shevchenko National University of Kyiv, Observatorna Str. 3, Kyiv, 04053 Ukraine
⁶¹ Max-Planck-Institut für extraterrestrische Physik, Gießenbachstraße 1, 85748 Garching, Germany
⁶² Oukaimeden Observatory (MOSS), Oukaimeden, Morocco
⁶³ Université Paris-Saclay, Université Paris Cité, CEA, CNRS, AIM, 91191 Gif-sur-Yvette, France
⁶⁴ Société Astronomique de France, Observatoire de Dauban, 04150 Banon, France
⁶⁵ Astronomy and Space Physics Department, Taras Shevchenko National University of Kyiv, Glushkova ave. 4, Kyiv, 03022 Ukraine
⁶⁶ National Center Junior academy of sciences of Ukraine, 38-44, Dehtiarivska St., Kyiv, 04119 Ukraine
⁶⁷ Main Astronomical Observatory of National Academy of Sciences of Ukraine, 27 Acad. Zabolotnoho Str., Kyiv, 03143 Ukraine
⁶⁸ Beijing Planetarium, Beijing Academy of Science and Technology, Beijing, 100044 PR China
⁶⁹ Observatoire de la Côte d’Azur, Université Côte d’Azur, CNRS, UMS, Galilée, France
⁷⁰ Xinjiang Astronomical Observatory, 150 Science 1-Street, Urumqi, Xinjiang, 830011 PR China
⁷¹ KNC Deep Sky Chile Observatory, Chile
⁷² Physics department and Tsinghua Center for Astrophysics, Tsinghua University, Beijing, 100084 PR China
⁷³ Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, A20, Datun Road, Chaoyang District, Beijing, 100012 PR China

Received: 11 September 2023
Accepted: 2 November 2023

Abstract

Aims. We present a campaign designed to train the Global Rapid Advanced Network Devoted to the Multi-messenger Addicts (GRANDMA) network and its infrastructure to follow up on transient alerts and detect their early afterglows. In preparation for O4 II campaign, we focused on gamma-ray burst (GRB) alerts since they are expected to serve as the electromagnetic counterpart of gravitational-wave events. Our goal was to improve our response to the alerts and to start prompt observations as soon as possible, so that we may better prepare the GRANDMA network for the fourth observational run of LIGO-Virgo-Kagra (launched at the end of May 2023) and future missions such as SM.

Methods. We set up a dedicated infrastructure and organized a rota of follow-up advocates (FAs) to guarantee round-the-clock assistance to our telescope teams, with an aim to receive, manage, and send out observational plans to our partner telescopes. To ensure a large number of observations, we focused on Swift GRBs whose localization errors were generally smaller than the GRANDMA telescopes’ field of view. This allowed us to bypass the transient identification process and focus on the reaction time and efficiency of the network.

Results. During the ‘Ready for O4 II’ phase, 11 Swift/INTEGRAL GRB triggers were selected. Of these, nine fields had been observed and three afterglows had been detected (GRB 220403B, GRB 220427A, GRB 220514A) with 17 GRANDMA telescopes and 17 amateur astronomers from the citizen science project Kilonova-Catcher. Here, we highlight the GRB 220427A analysis, where our long-term follow-up of the host galaxy allowed us to obtain a photometric redshift of z = 0.82 ± 0.09 and its lightcurve evolution, as well as to fit the decay slope of the afterglows and study the properties of the host galaxy.

Conclusions. During this eight-week-long GRB follow-up campaign, we successfully fulfilled our goal of training telescope teams for O4 and improving the associated technical toolkits. For seven of the GRB alerts, our network was able to start the first observations less than one hour after the GRB trigger time. We also characterized the network efficiency to observe GRB afterglow given the resulting time delay and limiting magnitude, and to its light curve evolution based on the observation of GRB 220427A.