ABSTRACT Long gamma-ray bursts are produced by energy dissipation within ultra-relativistic jets launched by newborn black holes after the collapse of a peculiar class of massive stars.

Right after the luminous and highly variable gamma-ray emission, a multi-wavelength afterglow is released by external dissipation of the jet energy in the medium that surrounds the

progenitor star. We report the discovery of a very bright (~10 mag) optical emission ~28 s after the explosion of the extremely luminous and energetic GRB 210619B located at redshift 1.937.

We observed the transition from a bright reverse to the forward shock emission, demonstrating that the early and late gamma-ray-burst multi-wavelength emission originated from a narrow,

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SHOCK EMISSION FROM GAMMA-RAY BURST 221009A Article Open access 29 June 2023 PROMPT-TO-AFTERGLOW TRANSITION OF OPTICAL EMISSION IN A LONG GAMMA-RAY BURST CONSISTENT WITH A FIREBALL Article

10 April 2023 GAMMA-RAY FLARES FROM RELATIVISTIC MAGNETIC RECONNECTION IN THE JET OF THE QUASAR 3C 279 Article Open access 21 August 2020 DATA AVAILABILITY Swift/XRT raw data are public and

available from the UK Swift Science Data Centre at the University of Leicester. The light curve data are available at: https://www.swift.ac.uk/xrt_curves/GRB_ID/flux.qdp where GRB_ID is the

GRB observation ID. The spectra were obtained at: https://www.swift.ac.uk/xrt_spectra/addspec.php?targ=GRB_ID. The details of the automatic spectral analysis are available at:

https://www.swift.ac.uk/xrt_spectra/docs.php. Fermi/LAT raw data are public and can be downloaded using GTBURST software at:

https://fermi.gsfc.nasa.gov/ssc/data/analysis/scitools/gtburst.html. Fermi/LAT 2nd GRB catalogue data are available at: https://www-glast.stanford.edu/pub_data/953/. All reduced data are

available from the corresponding author upon reasonable request. CODE AVAILABILITY HEASoft, Xspec and PyXspec are freely available at: https://heasarc.gsfc.nasa.gov/docs/software/heasoft,

https://heasarc.gsfc.nasa.gov/xanadu/xspec and https://heasarc.gsfc.nasa.gov/docs/xanadu/xspec/python/html/index.html. Gtburst is one of the Fermi Science Tools packages, freely available

at: https://fermi.gsfc.nasa.gov/ssc/data/analysis/software/. The details of the gtburst analysis can be found at: https://fermi.gsfc.nasa.gov/ssc/data/analysis/scitools/gtburst.html. The

emcee Python package is available at: https://emcee.readthedocs.io/en/stable/user/install/. All computer code is available from the corresponding author upon reasonable request. REFERENCES *

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_Astrophys. J._ 892, 97 (2020). ADS  Google Scholar  Download references ACKNOWLEDGEMENTS S.K. and M.P. acknowledge support from the European Structural and Investment Fund and the Czech

Ministry of Education, Youth and Sports (Project CoGraDS– CZ.02.1.01/0.0/0.0/15_003/0000437). FRAM-ORM operation is supported by the Czech Ministry of Education, Youth and Sports (project

numbers LM2015046, LM2018105 and LTT17006) and by the European Structural and Investment Fund and the Czech Ministry of Education, Youth and Sports (project numbers

CZ.02.1.01/0.0/0.0/16_013/0001403 and CZ.02.1.01/0.0/0.0/18_046/0016007). The research leading to these results has received funding from the European Union’s Horizon 2020 Programme under

the AHEAD2020 project (grant agreement number 871158). B.B. and M.B. acknowledge financial support from MIUR (PRIN 2017 grant number 20179ZF5KS). This research was supported under the

Ministry of Science and Higher Education of the Russian Federation grant number 075-15-2022-262 (13.MNPMU.21.0003). This work made use of data supplied by the UK Swift Science Data Centre at

the University of Leicester. AUTHOR INFORMATION AUTHORS AND AFFILIATIONS * Gran Sasso Science Institute, L’Aquila, Italy Gor Oganesyan, Samuele Ronchini, Biswajit Banerjee & Marica

Branchesi * INFN–Laboratori Nazionali del Gran Sasso, L’Aquila, Italy Gor Oganesyan, Samuele Ronchini, Biswajit Banerjee & Marica Branchesi * CEICO, Institute of Physics, Czech Academy

of Sciences, Prague, Czech Republic Sergey Karpov, Martin Mašek, Petr Janeček, Jan Ebr, Jakub Juryšek, Ronan Cunniffe & Michael Prouza * Special Astrophysical Observatory, Russian

Academy of Sciences, Nizhniy Arkhyz, Russia Sergey Karpov, Gregory Beskin & Nadezhda Lyapsina * Università degli Studi di Milano-Bicocca, Milano, Italy Om Sharan Salafia *

INAF–Osservatorio Astronomico di Brera, Merate, Italy Om Sharan Salafia * Astronomical Institute, Czech Academy of Sciences (ASU CAS), Ondřejov, Czech Republic Martin Jelínek, Jan Štrobl, 

Cyril Polášek & René Hudec * Kazan Federal University (KFU), Kazan, Russia Gregory Beskin, René Hudec, Anton Biryukov & Vyacheslav Sasyuk * Department of Astronomy and Astrophysics,

Pennsylvania State University, University Park, PA, USA Samuele Ronchini * Faculty of Electrical Engineering, Czech Technical University, Prague, Czech Republic René Hudec * OJS RPC PSI,

Nizhniy Arkhyz, Russia Eugeny Ivanov, Elena Katkova & Alexey Perkov * Sternberg Astronomical Institute, Moscow State University, Moscow, Russia Anton Biryukov * Faculty of Physics, HSE

University, Moscow, Russia Anton Biryukov Authors * Gor Oganesyan View author publications You can also search for this author inPubMed Google Scholar * Sergey Karpov View author

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this author inPubMed Google Scholar * Michael Prouza View author publications You can also search for this author inPubMed Google Scholar CONTRIBUTIONS S.K. carried out the analysis of the

optical data provided by D50, FRAM-ORM and MMT-9. G.O. analysed the Swift/XRT, Swift/BAT and Fermi/GBM data. G.O. and O.S.S. led the interpretation of the multi-wavelength afterglow

emission. G.O. led the writing of the paper. S.K. and O.S.S. provided major contributions to the writing of the paper. B.B. reduced the Fermi/LAT data. B.B. and S.R. collected the sample of

the bright optical light curves. S.R. conducted the comparison of GRB properties with the population of long GRBs in the Amati and Yonetoku relations. M.J., G.B., J.Š., C.P., R.H., E.I.,

E.K., A.P., A.B., N.L., V.S., M.M., P.J., J.E., J.J., R.C. and M.P. organized the observations, ensured the operation of and provided the data from D50, FRAM-ORM and MMT-9 telescopes. All

the authors contributed to discussions and edited the paper. CORRESPONDING AUTHOR Correspondence to Gor Oganesyan. ETHICS DECLARATIONS COMPETING INTERESTS The authors declare no competing

interests. PEER REVIEW PEER REVIEW INFORMATION _Nature Astronomy_ thanks Zhi-Ping Jin and Tanmoy Laskar for their contribution to the peer review of this work. ADDITIONAL INFORMATION

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permissions ABOUT THIS ARTICLE CITE THIS ARTICLE Oganesyan, G., Karpov, S., Salafia, O.S. _et al._ Exceptionally bright optical emission from a rare and distant gamma-ray burst. _Nat Astron_

7, 843–855 (2023). https://doi.org/10.1038/s41550-023-01972-4 Download citation * Received: 21 November 2021 * Accepted: 13 April 2023 * Published: 11 May 2023 * Issue Date: July 2023 *

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