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Background: Although research on children's motor competence is a growing field of interest, especially among young children (4-6 years), several questions remain to be answered. Differences in children’s motor competence and their determinants, must be made transparent since early childhood is a critical period for the development of fundamental movement skills, and thereby a lifelong active lifestyle and health. Objective: The purpose of this cross-sectional study was to determine differences in actual motor competence (AMC), perceived motor competence (PMC) and enjoyment of physical activity among young children with different weight status. Methods: AMC, PMC and enjoyment were measured among 1708 children (50.4% male, mean age: 5.34 ± 0.73 years) from 36 primary schools in The Netherlands. AMC was measured by using the Athletic Skills Track (AST-1). The Pictorial Scale of Perceived Movement Skill Competence for Young Children was used for determining PMC and enjoyment of physical activity was measured using a Visual Analogue Scale. The data were analyzed using a three-way ANOVA to examine the differences between AMC, PMC and enjoyment by sex (boys/girls), age (4, 5, 6 years) and weight status (normal, overweight, obesity). Results: Overall, AMC was ranked as ‘average motor gifted’. Average PMC and enjoyment scores were 3.31 (SE 0.01) (1-4 scale) and 4.41 (SE 0.02) (1-5 scale) respectively. No interaction effects were found between sex, age and weight status on AMC or PMC. However, there was a statistically significant two-way interaction effect for enjoyment between age and weight status (F (4,1454) =2.464, p =.043). Relative enjoyment scores for normal weight and overweight groups between high and low enjoyment were distributed 99% to 1%. However, in the obese group there was a distribution of 92% to 8% between high and low enjoyment. Conclusions: The results of this study suggest that there are no significant differences in AMC and PMC between children of different sex, ages (4, 5 and 6 years), and weight status in this age group. However, children with obesity more often experience less enjoyment during physical activity than children with another weight status. Targeted intervention for increasing enjoyment during physical activity in combination with reducing obesity seems advisable even at young age.

Full list of authors: Buckley, D. A. H.; Bagnulo, S.; Britto, R. J.; Mao, J.; Kann, D. A.; Cooper, J.; Lipunov, V.; Hewitt, D. M.; Razzaque, S.; Kuin, N. P. M.; Monageng, I. M.; Covino, S.; Jakobsson, P.; van der Horst, A. J.; Wiersema, K.; Böttcher, M.; Campana, S.; D'Elia, V.; Gorbovskoy, E. S.; Gorbunov, I.; Groenewald, D. N.; Hartmann, D. H.; Kornilov, V. G.; Mundell, C. G.; Podesta, R.; Thomas, J. K.; Tyurina, N.; Vlasenko, D.; van Soelen, B.; Xu, D., We report on results of spectropolarimetry of the afterglow of the long gamma-ray burst GRB 191221B, obtained with SALT/RSS and VLT/FORS2, as well as photometry from two telescopes in the MASTER Global Robotic Network, at the MASTER-SAAO (South Africa) and MASTER-OAFA (Argentina) stations. Prompt optical emission was detected by MASTER-SAAO 38 s after the alert, which dimmed from a magnitude (white-light) of ∼10-16.2 mag over a period of ∼10 ks, followed by a plateau phase lasting ∼10 ks and then a decline to ∼18 mag after 80 ks. The light curve shows complex structure, with four or five distinct breaks in the power-law decline rate. SALT/RSS linear spectropolarimetry of the afterglow began ∼2.9 h after the burst, during the early part of the plateau phase of the light curve. Absorption lines seen at ∼6010 and 5490 Å are identified with the Mg ii 2799 Å line from the host galaxy at z = 1.15 and an intervening system located at z = 0.96. The mean linear polarization measured over 3400-8000 Å was ∼1.5 per cent and the mean equatorial position angle (θ) was ∼65°. VLT/FORS2 spectropolarimetry was obtained ∼10 h post-burst, during a period of slow decline (α = -0.44), and the polarization was measured to be p = 1.2 per cent and θ = 60°. Two observations with the MeerKAT radio telescope, taken 30 and 444 d after the GRB trigger, detected radio emission from the host galaxy only. We interpret the light curve and polarization of this long GRB in terms of a slow-cooling forward shock. © 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society., Some of the observations presented here were obtained with SALT under programme 2018-2-LSP-001 (PI: DAHB), which is supported by Poland under grant no. MNiSW DIR/WK/2016/07. Based on observations collected at the European Southern Observatory under ESO programme 0104.D-0600(C). DAHB and JT acknowledge support through the National Research Foundation (NRF) of South Africa. MB is supported by the South African Research Chairs Initiative (grant no. 64789) of the Department of Science and Innovation and the NRF.5 DMH acknowledges financial support from the NRF and the SAAO. SR is partially supported by NRF with grant no. 111749 (CPRR) and by a University of Johannesburg Research Council grant. DAK acknowledges support from Spanish National Research Project RTI2018-098104-J-I00 (GRBPhot). NPMK acknowledges support by the UK Space Agency. MASTER (equipment) is supported by Lomonosov Moscow State University Development Program. VL and DV are supported by RFBR grant 19-29-11011. CGM acknowledges financial support from Hiroko and Jim Sherwin. We thank the Director and staff of SARAO for supporting our MeerKAT DDT observation. The MeerKAT telescope is operated by the South African Radio Astronomy Observatory (SARAO), which is a facility of the National Research Foundation, an agency of the Department of Science and Innovation. Based on observations made with the SALT and the MeerKAT radio telescope array., With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709.

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited., Gamma-ray bursts (GRBs) are fascinating events due to their panchromatic nature. We study optical plateaus in GRB afterglows via an extended search into archival data. We comprehensively analyze all published GRBs with known redshifts and optical plateaus observed by many ground-based telescopes (e.g., Subaru Telescope, RATIR) around the world and several space-based observatories such as the Neil Gehrels Swift Observatory. We fit 500 optical light curves, showing the existence of the plateau in 179 cases. This sample is 75% larger than the previous one, and it is the largest compilation so far of optical plateaus. We discover the 3D fundamental plane relation at optical wavelengths using this sample. This correlation is between the rest-frame time at the end of the plateau emission, ${T}_{\mathrm{opt}}^{* }$, its optical luminosity, Lopt, and the peak in the optical prompt emission, Lpeak,opt, thus resembling the three-dimensional (3D) X-ray fundamental plane (the so-called 3D Dainotti relation). We correct our sample for redshift evolution and selection effects, discovering that this correlation is indeed intrinsic to GRB physics. We investigate the rest-frame end-time distributions in X-rays and optical (${T}_{\mathrm{opt}}^{* }$, ${T}_{{\rm{X}}}^{* }$), and conclude that the plateau is achromatic only when selection biases are not considered. We also investigate if the 3D optical correlation may be a new discriminant between optical GRB classes and find that there is no significant separation between the classes compared to the Gold sample plane after correcting for evolution. © 2022. The Author(s). Published by the American Astronomical Society., D.A.K. acknowledges support from Spanish National Research Project RTI2018-098104-J-I00 (GRBPhot). S.Y. and D.L. acknowledge the support by the United States Department of Energy in funding the Science Undergraduate Laboratory Internship (SULI) program. S.Y. gratefully acknowledges the support of the Vagelos Challenge Award at the University of Pennsylvania. R.L.B. acknowledges support from the DGAPA/UNAM IG100820 and the DGAPA/UNAM postdoctoral fellowship. N.F. acknowledges support from the DGAPA/UNAM IN106521. Some of the data used in this paper were acquired with the RATIR instrument, funded by the University of California and NASA Goddard Space Flight Center, and the 1.5-meter Harold L. Johnson telescope at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, operated and maintained by the Observatorio Astronómico Nacional and the Instituto de Astronomía of the Universidad Nacional Autónoma de México. Operations are partially funded by the Universidad Nacional Autónoma de México (DGAPA/PAPIIT IG100414, IT102715, AG100317, IN109418, IG100820, IN106521, and IN105921). We acknowledge the contribution of Leonid Georgiev and Neil Gehrels to the development of RATIR. M.F., L.Z., and A.Z. are grateful for the support from the Scientific Caribbean Foundation. E.S. thanks the Latino Education Advancement Foundation for their support., With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709.

The temporal and spectral evolution of gamma-ray burst (GRB) afterglows can be used to infer the density and density profile of the medium through which the shock is propagating. In long-duration (core-collapse) GRBs, the circumstellar medium (CSM) is expected to resemble a wind-blown bubble, with a termination shock, separating the stellar wind and the interstellar medium (ISM). A long standing problem is that flat density profiles, indicative of the ISM, are often found at lower radii than expected for a massive star progenitor. Furthermore, the presence of both wind-like environments at high radii and ISM-like environments at low radii remains a mystery. In this paper, we perform a ‘CSM population synthesis’ with long GRB progenitor stellar evolution models. Analytic results for the evolution of wind blown bubbles are adjusted through comparison with a grid of 2D hydrodynamical simulations. Predictions for the emission radii, ratio of ISM to wind-like environments, wind, and ISM densities are compared with the largest sample of afterglow derived parameters yet compiled, which we make available for the community. We find that high ISM densities of n ∼ 1000 cm−3 best reproduce observations. If long GRBs instead occur in typical ISM densities of n ∼ 1 cm−3, then the discrepancy between theory and observations is shown to persist at a population level. We discuss possible explanations for the origin of variety in long GRB afterglows, and for the overall trend of CSM modelling to over-predict the termination shock radius. © 2022 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society., BPG and MN are supported by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 948381). DAK acknowledges support from Spanish National Research Project RTI2018-098104-J-I00 (GRBPhot). AJvM is supported by the ANR-19-CE31-0014GAMALO project. AJL has received funding from the European Research Council (ERC) under the European Union’s Seventh Framework Programme (FP7-2007-2013) (Grant agreement No. 725246). ERS has been supported by STFC consolidated grant ST/P000495/1. PJG is supported by NRF SARChI Grant 111692. We gratefully acknowledge the use of GOTOHEAD, the computing cluster of the Gravitational-wave Optical Transient Observer (GOTO), as well as support from Joe Lyman and Krzysztof Ulaczyk., With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709.

Full list of authors: Rastinejad, Jillian C.; Gompertz, Benjamin P.; Levan, Andrew J.; Fong, Wen-Fai; Nicholl, Matt; Lamb, Gavin P.; Malesani, Daniele B.; Nugent, Anya E.; Oates, Samantha R.; Tanvir, Nial R.; Postigo, Antonio de Ugarte; Kilpatrick, Charles D.; Moore, Christopher J.; Metzger, Brian D.; Ravasio, Maria Edvige; Rossi, Andrea; Schroeder, Genevieve; Jencson, Jacob; Sand, David J.; Smith, Nathan; Fernandez, Jose Feliciano Agui; Berger, Edo; Blanchard, Peter K.; Chornock, Ryan; Cobb, Bethany E.; De Pasquale, Massimiliano; Fynbo, Johan P. U.; Izzo, Luca; Kann, D. Alexander; Laskar, Tanmoy; Marini, Ester; Paterson, Kerry; Escorial, Alicia Rouco; Sears, Huei M.; Thone, Christina C., Gamma-ray bursts (GRBs) are divided into two populations1,2; long GRBs that derive from the core collapse of massive stars (for example, ref. 3) and short GRBs that form in the merger of two compact objects4,5. Although it is common to divide the two populations at a gamma-ray duration of 2 s, classification based on duration does not always map to the progenitor. Notably, GRBs with short (≲2 s) spikes of prompt gamma-ray emission followed by prolonged, spectrally softer extended emission (EE-SGRBs) have been suggested to arise from compact object mergers6,7,8. Compact object mergers are of great astrophysical importance as the only confirmed site of rapid neutron capture (r-process) nucleosynthesis, observed in the form of so-called kilonovae9,10,11,12,13,14. Here we report the discovery of a possible kilonova associated with the nearby (350 Mpc), minute-duration GRB 211211A. The kilonova implies that the progenitor is a compact object merger, suggesting that GRBs with long, complex light curves can be spawned from merger events. The kilonova of GRB 211211A has a similar luminosity, duration and colour to that which accompanied the gravitational wave (GW)-detected binary neutron star (BNS) merger GW170817 (ref. 4). Further searches for GW signals coincident with long GRBs are a promising route for future multi-messenger astronomy. © 2022, The Author(s), under exclusive licence to Springer Nature Limited., The Fong group at Northwestern acknowledges support by the National Science Foundation under grant nos. AST-1814782 and AST-1909358 and CAREER grant no. AST-2047919. W.F. gratefully acknowledges support by the David and Lucile Packard Foundation. A.J.L. and D.B.M. are supported by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 725246). M.N. and B.P.G. are supported by the ERC under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 948381). M.N. acknowledges a Turing Fellowship. G.P.L. is supported by the UK Science and Technology Facilities Council grant ST/S000453/1. A.R. and E.M. acknowledge support from the INAF research project ‘LBT - Supporto Arizona Italia’. J.F.A.F. acknowledges support from the Spanish Ministerio de Ciencia, Innovación y Universidades through the grant PRE2018-086507. D.A.K. and J.F.A.F. acknowledge support from Spanish National Research Project RTI2018-098104-J-I00 (GRBPhot). W. M. Keck Observatory and MMT Observatory access was supported by Northwestern University and the Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA). Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration (NASA). The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. We wish to recognize and acknowledge the very important cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. Observations reported here were obtained at the MMT Observatory, a joint facility of the University of Arizona and the Smithsonian Institution. On the basis of observations obtained at the international Gemini Observatory (programme ID GN2021B-Q-109), a programme of NOIRLab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation on behalf of the Gemini Observatory partnership: the National Science Foundation (United States), National Research Council (Canada), Agencia Nacional de Investigación y Desarrollo (Chile), Ministerio de Ciencia, Tecnología e Innovación (Argentina), Ministério da Ciência, Tecnologia, Inovações e Comunicações (Brazil) and Korea Astronomy and Space Science Institute (Republic of Korea). Processed using the Gemini IRAF package and DRAGONS (Data Reduction for Astronomy from Gemini Observatory North and South). This work made use of data supplied by the UK Swift Science Data Centre at the University of Leicester. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. This research is based on observations made with the NASA/ESA Hubble Space Telescope obtained from the Space Telescope Science Institute, which is operated by the AURA, Inc., under NASA contract NAS 5-26555. These observations are associated with programme no. 16923. This work is partly based on observations made with the Gran Telescopio Canarias, installed at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, on the island of La Palma. Partly based on observations collected at the Calar Alto Astronomical Observatory, operated jointly by Instituto de Astrofísica de Andalucía (CSIC) and Junta de Andalucía. Partly based on observations made with the Nordic Optical Telescope, under programme 64-502, owned in collaboration by the University of Turku and Aarhus University, and operated jointly by Aarhus University, the University of Turku and the University of Oslo, representing Denmark, Finland and Norway, respectively, the University of Iceland and Stockholm University at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofísica de Canarias. The LBT is an international collaboration among institutions in the United States, Italy and Germany. LBT Corporation partners are: The University of Arizona on behalf of the Arizona Board of Regents; Istituto Nazionale di Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max Planck Society, The Leibniz Institute for Astrophysics Potsdam and Heidelberg University; The Ohio State University, representing OSU, University of Notre Dame, University of Minnesota and University of Virginia.

Full list of authors: Aivazyan, V; Almualla, M.; Antier, S.; Baransky, A.; Barynova, K.; Basa, S.; Bayard, F.; Beradze, S.; Berezin, D.; Blazek, M.; Boutigny, D.; Boust, D.; Broens, E.; Burkhonov, O.; Cailleau, A.; Christensen, N.; Cejudo, D.; Coleiro, A.; Coughlin, M. W.; Datashvili, D.; Dietrich, T.; Dolon, F.; Ducoin, J-G; Duverne, P-A; Marchal-Duval, G.; Galdies, C.; Granier, L.; Godunova, V; Gokuldass, P.; Eggenstein, H. B.; Freeberg, M.; Hello, P.; Inasaridze, R.; Ishida, E. E. O.; Jaquiery, P.; Kann, D. A.; Kapanadze, G.; Karpov, S.; Kiendrebeogo, R. W.; Klotz, A.; Kneip, R.; Kochiashvili, N.; Kou, W.; Kugel, F.; Lachaud, C.; Leonini, S.; Leroy, A.; Leroy, N.; Su, A. Le Van; Marchais, D.; Midavaine, T.; Moeller, A.; Morris, D.; Natsvlishvili, R.; Navarete, F.; Noysena, K.; Nissanke, S.; Noonan, K.; Orange, N. B.; Peloton, J.; Popowicz, A.; Pradier, T.; Prouza, M.; Raaijmakers, G.; Rajabov, Y.; Richmond, M.; Romanyuk, Ya; Rousselot, L.; Sadibekova, T.; Serrau, M.; Sokoliuk, O.; Song, X.; Simon, A.; Stachie, C.; Taylor, A.; Tillayev, Y.; Turpin, D.; Vardosanidze, M.; Vlieghe, J.; Tosta e Melo, I; Wang, X. F.; Zhu, J., We present our follow-up observations with GRANDMA of transient sources revealed by the Zwicky Transient Facility (ZTF). Over a period of six months, all ZTF alerts were examined in real time by a dedicated science module implemented in the Fink broker, which will be used in filtering of transients discovered by the Vera C. Rubin Observatory. In this article, we present three selection methods to identify kilonova candidates. Out of more than 35 million alerts, a hundred sources have passed our selection criteria. Six were then followed-up by GRANDMA (by both professional and amateur astronomers). The majority were finally classified either as asteroids or as supernovae events. We mobilized 37 telescopes, bringing together a large sample of images, taken under various conditions and quality. To complement the orphan kilonova candidates, we included three additional supernovae alerts to conduct further observations during summer 2021. We demonstrate the importance of the amateur astronomer community that contributed images for scientific analyses of new sources discovered in a magnitude range r′ = 17 − 19 mag. We based our rapid kilonova classification on the decay rate of the optical source that should exceed 0.3 mag d−1. GRANDMA’s follow-up determined the fading rate within 1.5 ± 1.2 d post-discovery, without waiting for further observations from ZTF. No confirmed kilonovae were discovered during our observing campaign. This work will be continued in the coming months in the view of preparing for kilonova searches in the next gravitational-wave observing run O4. © 2022 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society., SA and CL acknowledge the financial support of the Programme National Hautes Energies (PNHE). SA acknowledges the financial support of CNES. SA is grateful for financial support from the Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO) through the VIDI (PI: Nissanke). SA dedicates her contribution to Rayan Ouram, who is a source of inspiration for bravity and humanity for GRANDMA. DT acknowledges the financial support of CNES post-doctoral program. UBAI acknowledges support from the Ministry of Innovative Development through projects FA-Atech-2018-392 and VA-FA-F-2-010. RI acknowledges Shota Rustaveli National Science Foundation (SRNSF) grant No - RF/18-1193. TAROT. has been built with the support of the Institut National des Sciences de l’Univers, CNRS, France. MP, SK, and MM are supported by European Structural and Investment Fund and the Czech Ministry of Education, Youth and Sports (Projects CZ.02.1.01/0.0/0.0/16_013/0001403, CZ.02.1.01/0.0/0.0/18_046/0016007 and CZ.02.1.01/0.0/0.0/15_003/0000437). The FRAM telescope is also supported by the Czech Ministry of Education, Youth and Sports (projects LM2015046, LM2018105, LTT17006). NBO and DM acknowledge financial support from NASA MUREP MIRO award 80NSSC21M0001, NASA EPSCoR award 80NSSC19M0060, and NSF EiR award 1901296. PG acknowledges financial support from NSF EiR award 1901296. DAK acknowledges support from Spanish National Research Project RTI2018-098104-J-I00 (GRBPhot) XW is supported by the National Science Foundation of China (NSFC grants 12033003 and 11633002), the Scholar Program of Beijing Academy of Science and Technology (DZ:BS202002), and the Tencent Xplorer Prize. The work of FN is supported by NOIRLab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation. The GRANDMA consortium thank the amateur participants to the kilonova-catcher program. The kilonova-catcher program is supported by the IdEx Université de Paris, ANR-18-IDEX-0001. This research made use of the cross-match service provided by CDS, Strasbourg. MC acknowledges support from the National Science Foundation with grant numbers PHY-2010970 and OAC-2117997. GR acknowledges financial support from the Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO) through the Projectruimte and VIDI grants (PI: Nissanke). Thanks to the National Astronomical Research Institute of Thailand (Public Organization), based on observations made with the Thai Robotic Telescope under program ID TRTC08D_005 and TRTC09A_002. S., With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709.

Full list of authors: Ho, Anna Y. Q.; Perley, Daniel A.; Yao, Yuhan; Svinkin, Dmitry; Postigo, A. de Ugarte; Perley, R. A.; Kann, D. Alexander; Burns, Eric; Andreoni, Igor; Bellm, Eric C.; Bissaldi, Elisabetta; Bloom, Joshua S.; Brink, Thomas G.; Dekany, Richard; Drake, Andrew J.; Fernandez, Jose Feliciano Agui; Filippenko, Alexei, V; Frederiks, Dmitry; Graham, Matthew J.; Hristov, Boyan A.; Kasliwal, Mansi M.; Kulkarni, S. R.; Kumar, Harsh; Laher, Russ R.; Lysenko, Alexandra L.; Mailyan, Bagrat; Malacaria, Christian; Miller, A. A.; Poolakkil, S.; Riddle, Reed; Ridnaia, Anna; Rusholme, Ben; Savchenko, Volodymyr; Sollerman, Jesper; Thoene, Christina; Tsvetkova, Anastasia; Ulanov, Mikhail; von Kienlin, Andreas.--This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited., Dirty fireballs are a hypothesized class of relativistic massive-star explosions with an initial Lorentz factor Γinit below the Γinit ∼ 100 required to produce a long-duration gamma-ray burst (LGRB), but which could still produce optical emission resembling LGRB afterglows. Here we present the results of a search for on-axis optical afterglows using the Zwicky Transient Facility (ZTF). Our search yielded seven optical transients that resemble on-axis LGRB afterglows in terms of their red colors (g − r > 0 mag), faint host galaxies (r > 23 mag), rapid fading (dr/dt > 1 mag day−1), and in some cases X-ray and radio emission. Spectroscopy of the transient emission within a few days of discovery established cosmological distances (redshift z = 0.876 to 2.9) for six of the seven events, tripling the number of afterglows with redshift measurements discovered by optical surveys without a γ-ray trigger. A likely associated LGRB (GRB 200524A, GRB 210204A, GRB 210212B, and GRB 210610B) was identified for four events (ZTF 20abbiixp/AT 2020kym, ZTF 21aagwbjr/AT 2021buv, ZTF 21aakruew/AT 2021cwd, and ZTF 21abfmpwn/AT 2021qbd) post facto, while three (ZTF 20aajnksq/AT 2020blt, ZTF 21aaeyldq/AT 2021any, and ZTF 21aayokph/AT 2021lfa) had no detected LGRB counterpart. The simplest explanation for the three "orphan" events is that they were regular LGRBs missed by high-energy satellites owing to detector sensitivity and duty cycle, although it is possible that they were intrinsically subluminous in γ-rays or viewed slightly off-axis. We rule out a scenario in which dirty fireballs have a similar energy per solid angle to LGRBs and are an order of magnitude more common. In addition, we set the first direct constraint on the ratio of the opening angles of the material producing γ-rays and the material producing early optical afterglow emission, finding that they must be comparable. © 2022. The Author(s). Published by the American Astronomical Society., D.A.P.'s contribution was performed in part at the Aspen Center for Physics, which is supported by National Science Foundation (NSF) grant PHY-1607611. This work was partially supported by a grant from the Simons Foundation. D.F., A.T., and M.U. acknowledge support from RSF grant 21-12-00250. D.A.K. and J.F.A.F acknowledges support from Spanish National Research Project RTI2018-098104-J-I00 (GRBPhot). H.K. thanks the LSSTC Data Science Fellowship Program, which is funded by LSSTC, NSF Cybertraining Grant #1829740, Brinson and Moore Foundations. J.F.A.F. acknowledges support from the Spanish Ministerio de Ciencia, Innovación y Universidades through the grant PRE2018-086507. A.V.F.'s group at U.C. Berkeley is grateful for assistance from the Christopher R. Redlich Fund and many individual donors., With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709.

Full list of authors: Rossi, A.; Frederiks, D. D.; Kann, D. A.; De Pasquale, M.; Pian, E.; Lamb, G.; D'Avanzo, P.; Izzo, L.; Levan, A. J.; Malesani, D. B.; Melandri, A.; Guelbenzu, A. Nicuesa; Schulze, S.; Strausbaugh, R.; Tanvir, N. R.; Amati, L.; Campana, S.; Cucchiara, A.; Ghirlanda, G.; Della Valle, M.; Klose, S.; Salvaterra, R.; Starling, R. L. C.; Stratta, G.; Tsvetkova, A. E.; Vergani, S. D.; D'Ai, A.; Burgarella, D.; Covino, S.; D'Elia, V; Postigo, A. de Ugarte; Fausey, H.; Fynbo, J. P. U.; Frontera, F.; Guidorzi, C.; Heintz, K. E.; Masetti, N.; Maiorano, F.; Mundell, C. G.; Oates, S. R.; Page, M. J.; Palazzi, E.; Palmerio, J.; Pugliese, G.; Rau, A.; Saccardi, A.; Sbarufatti, B.; Svinkin, D. S.; Tagliaferri, G.; van der Horst, A. J.; Watson, D. J.; Ulanov, M., V; Wiersema, K.; Xu, D.; Zhang, J.--This is an Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited., We present a detailed follow-up of the very energetic GRB 210905A at a high redshift of z = 6.312 and its luminous X-ray and optical afterglow. Following the detection by Swift and Konus-Wind, we obtained a photometric and spectroscopic follow-up in the optical and near-infrared (NIR), covering both the prompt and afterglow emission from a few minutes up to 20 Ms after burst. With an isotropic gamma-ray energy release of Eiso = 1.27−0.19+0.20 × 1054 erg, GRB 210905A lies in the top ∼7% of gamma-ray bursts (GRBs) in the Konus-Wind catalogue in terms of energy released. Its afterglow is among the most luminous ever observed, and, in particular, it is one of the most luminous in the optical at t ≳ 0.5 d in the rest frame. The afterglow starts with a shallow evolution that can be explained by energy injection, and it is followed by a steeper decay, while the spectral energy distribution is in agreement with slow cooling in a constant-density environment within the standard fireball theory. A jet break at ∼46.2 ± 16.3 d (6.3 ± 2.2 d rest-frame) has been observed in the X-ray light curve; however, it is hidden in the H band due to a constant contribution from the host galaxy and potentially from a foreground intervening galaxy. In particular, the host galaxy is only the fourth GRB host at z > 6 known to date. By assuming a number density n = 1 cm−3 and an efficiency η = 0.2, we derived a half-opening angle of 8.4 ° ±1.0°, which is the highest ever measured for a z ≳ 6 burst, but within the range covered by closer events. The resulting collimation-corrected gamma-ray energy release of ≃1 × 1052 erg is also among the highest ever measured. The moderately large half-opening angle argues against recent claims of an inverse dependence of the half-opening angle on the redshift. The total jet energy is likely too large to be sustained by a standard magnetar, and it suggests that the central engine of this burst was a newly formed black hole. Despite the outstanding energetics and luminosity of both GRB 210905A and its afterglow, we demonstrate that they are consistent within 2σ with those of less distant bursts, indicating that the powering mechanisms and progenitors do not evolve significantly with redshift. © A. Rossi et al. 2022., A. Rossi acknowledges support from the INAF project Premiale Supporto Arizona & Italia. D.D.F. and A.E.T. acknowledge support from RSF grant 21-12-00250. D.A.K. acknowledges support from Spanish National Research Project RTI2018-098104-J-I00 (GRBPhot). A.R., E.Pal., P.D.A., L.A., E.Pi., G.S., S.C., V.D.E., M.D.V., and A.M. acknowledge support from PRIN-MIUR 2017 (grant 20179ZF5KS). P.D.A., A.M. acknowledge support from the Italian Space Agency, contract ASI/INAF n. I/004/11/5. L.I. was supported by grants from VILLUM FONDEN (project number 16599 and 25501). D.B.M. and A.J.L. acknowledge the European Research Council (ERC) under the European Union’s Seventh Framework programme (FP7-2007-2013) (grant agreement No. 725246). The Cosmic Dawn Center (DAWN) is funded by the Danish National Research Foundation under grant No. 140. K.E.H. acknowledges support by a Postdoctoral Fellowship Grant (217690–051) from The Icelandic Research Fund. C.G.M. acknowledges financial support from Hiroko and Jim Sherwin. Part of the funding for GROND (both hardware as well as personnel) was generously granted from the Leibniz-Prize to Prof. G. Hasinger (DFG grant HA 1850/28-1). This work made use of data supplied by the UK Swift Science Data Centre at the University of Leicester., With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709.

Full list of authors: Saccardi, A.; Vergani, S. D.; De Cia, A.; D'Elia, V.; Heintz, K. E.; Izzo, L.; Palmerio, J. T.; Petitjean, P.; Rossi, A.; Postigo, A. de Ugarte; Christensen, L.; Konstantopoulou, C.; Levan, A. J.; Malesani, D. B.; Moller, P.; Ramburuth-Hurt, T.; Salvaterra, R.; Tanvir, N. R.; Thone, C. C.; Vejlgaard, S.; Fynbo, J. P. U.; Kann, D. A.; Schady, P.; Watson, D. J.; Wiersema, K.; Campana, S.; Covino, S.; De Pasquale, M.; Fausey, H.; Hartmann, D. H.; van der Horst, A. J.; Jakobsson, P.; Palazzi, E.; Pugliese, G.; Savaglio, S.; Starling, R. L. C.; Stratta, G.; Zafar, T.-- This is an Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited., The study of the properties of galaxies in the first billion years after the Big Bang is one of the major topics of current astrophysics. Optical and near-infrared spectroscopy of the afterglows of long gamma-ray bursts (GRBs) provides a powerful diagnostic tool to probe the interstellar medium (ISM) of their host galaxies and foreground absorbers, even up to the highest redshifts. We analyze the VLT/X-shooter afterglow spectrum of GRB 210905A, triggered by the Neil Gehrels Swift Observatory, and detect neutral hydrogen, low-ionization, high-ionization, and fine-structure absorption lines from a complex system at z = 6.3118, which we associate with the GRB host galaxy. We use them to study the ISM properties of the host system, revealing the metallicity, kinematics, and chemical abundance pattern of its gas along the GRB line of sight. We also detect absorption lines from at least two foreground absorbers at z = 5.7390 and z = 2.8296. The total metallicity of the z ∼ 6.3 system is [M/H]tot = −1.72 ± 0.13, after correcting for dust depletion and taking α-element enhancement into account, as suggested by our analysis. This is consistent with the values found for the other two GRBs at z ∼ 6 with spectroscopic data showing metal absorption lines (GRB 050904 and GRB 130606A), and it is at the higher end of the metallicity distribution of quasar damped Lyman-α systems (QSO-DLAs) extrapolated to such a high redshift. In addition, we determine the overall amount of dust and dust-to-metal mass ratio (DTM) ([Zn/Fe]fit = 0.33 ± 0.09 and DTM = 0.18 ± 0.03). We find indications of nucleosynthesis due to massive stars and, for some of the components of the gas clouds, we find evidence of peculiar nucleosynthesis, with an overabundance of aluminum (as also found for GRB 130606A). From the analysis of fine-structure lines, we determine distances of several kiloparsecs for the low-ionization gas clouds closest to the GRB. Those are farther distances than usually found for GRB host absorption systems, possibly due to the very high number of ionizing photons produced by the GRB that could ionize the line of sight up to several hundreds of parsecs. Using the HST/F140W image of the GRB field, we show the GRB host galaxy (with a possible afterglow contamination) as well as multiple objects within 2″ from the GRB position. We discuss the galaxy structure and kinematics that could explain our observations, also taking into account a tentative detection of Lyman-α emission at z = 6.3449 (∼1200 km s−1 from the GRB redshift in velocity space), and the observational properties of Lyman-α emitters at very high redshift. This study shows the amazing potential of GRBs to access detailed information on the properties (metal enrichment, gas kinematic, dust content, nucleosynthesis...) of very high-redshift galaxies, independently of the galaxy luminosity. Deep spectroscopic observations with VLT/MUSE and JWST will offer the unique possibility of combining the information presented in this paper with the properties of the ionized gas, with the goal of better understanding how galaxies in the reionization era form and evolve. © The Authors 2023., This work was supported by CNES. A.S. and S.D.V. acknowledge support from DIM-ACAV+. D.A.K. acknowledges support from Spanish National Research Project RTI2018-098104-J-I00 (GRBPhot). A.J.L. and D.B.M. are supported by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 725246). The Cosmic Dawn Center is funded by the Danish National Research Foundation under grant No. 140. NRT is supported by STFC consolidated grant ST/W000857/1. A.R., E.P., G.S. and S.S. acknowledge support from PRIN-MIUR 2017 (grant 20179ZF5KS). G.S. acknowledges the support by the State of Hesse within the Research Cluster ELEMENTS (Project ID 500/10.006)., With funding from the Spanish government through the "Severo Ochoa Centre of Excellence" accreditation (CEX2021-001131-S).

Full list of authors: Melandri, A.; Izzo, L. ; Pian, E.; Malesani, D. B.; Della Valle, M.; Rossi, A.; D'Avanzo, P.; Guetta, D.; Mazzali, P. A.; Benetti, S.; Masetti, N.; Palazzi, E.; Savaglio, S.; Amati, L.; Antonelli, L. A.; Ashall, C.; Bernardini, M. G.; Campana, S.; Carini, R.; Covino, S.; D'Elia, V.; de Ugarte Postigo, A.; De Pasquale, M.; Filippenko, A. V.; Fruchter, A. S.; Fynbo, J. P. U.; Giunta, A.; Hartmann, D. H.; Jakobsson, P.; Japelj, J.; Jonker, P. G.; Kann, D. A.; Lamb, G. P.; Levan, A. J.; Martin-Carrillo, A.; Møller, P.; Piranomonte, S.; Pugliese, G.; Salvaterra, R.; Schulze, S.; Starling, R. L. C.; Stella, L.; Tagliaferri, G.; Tanvir, N.; Watson, D., We observed GRB 190114C (redshift z = 0.4245), the first gamma-ray burst (GRB) ever detected at TeV energies, at optical and near-infrared wavelengths with several ground-based telescopes and the Hubble Space Telescope, with the primary goal of studying its underlying supernova, SN 2019jrj. The monitoring spanned the time interval between 1.3 and 370 days after the burst, in the observer frame. We find that the afterglow emission can be modelled with a forward shock propagating in a uniform medium modified by time-variable extinction along the line of sight. A jet break could be present after 7 rest-frame days, and accordingly the maximum luminosity of the underlying supernova (SN) ranges between that of stripped-envelope core-collapse SNe of intermediate luminosity and that of the luminous GRB-associated SN 2013dx. The observed spectral absorption lines of SN 2019jrj are not as broad as in classical GRB SNe and are instead more similar to those of less-luminous core-collapse SNe. Taking the broad-lined stripped-envelope core-collapse SN 2004aw as an analogue, we tentatively derive the basic physical properties of SN 2019jrj. We discuss the possibility that a fraction of the TeV emission of this source might have had a hadronic origin and estimate the expected high-energy neutrino detection level with IceCube. © ESO 2022., A. M., M. G. B., P. D. A., S. C., and G. T. acknowledge support from ASI grant I/004/11/5. P. D. A., M. D. V., E. Pa., S. Sa., and S. P. acknowledge support from PRIN-MIUR 2017 (grant 20179ZF5KS). L. I. was supported by the VILLUM FONDEN (project numbers 16599 and 25501). D. B. M. acknowledges support from research grant 19054 from VILLUM FONDEN. A. V. F.'s research is supported by the Christopher R. Redlich Fund, the Miller Institute for Basic Research in Science (in which he is a Senior Miller Fellow), and many individual donors. D. A. K. acknowledges support from Spanish National Research Project RTI2018-098104-JI00 (GRBPhot). D. W. is supported by Independent Research Fund Denmark grant DFF-7014-00017. The Cosmic Dawn Center is supported by the Danish National Research Foundation under grant 140. A. R. acknowledges support from the project Supporto Arizona and Italia. The LBT is an international collaboration among institutions in the United States, Italy, and Germany. LBT Corporation partners are The University of Arizona on behalf of the Arizona Board of Regents; Istituto Nazionale di Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, The Leibniz Institute for Astrophysics Potsdam, and Heidelberg University; The Ohio State University, representing OSU, University of Notre Dame, University of Minnesota, and University of Virginia. This work made use of data supplied by the UK Swift Science Data Centre at the University of Leicester., With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709.

This is an Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited., Context. Scientific interest in studying high-energy transient phenomena in the Universe has risen sharply over the last decade. At present, multiple ground-based survey projects have emerged to continuously monitor the optical (and multi-messenger) transient sky at higher image cadences and covering ever larger portions of the sky every night. These novel approaches are leading to a substantial increase in global alert rates, which need to be handled with care, especially with regard to keeping the level of false alarms as low as possible. Therefore, the standard transient detection pipelines previously designed for narrow field-of-view instruments must now integrate more sophisticated tools to deal with the growing number and diversity of alerts and false alarms. Aims. Deep machine learning algorithms have now proven their efficiency in recognising patterns in images. These methods are now used in astrophysics to perform different classification tasks such as identifying bogus from real transient point-like sources. We explore this method to provide a robust and flexible algorithm that could be included in any kind of transient detection pipeline. Methods. We built a convolutional neural network (CNN) algorithm in order to perform a ‘real or bogus’ classification task on transient candidate cutouts (subtraction residuals) provided by different kinds of optical telescopes. The training involved human-supervised labelling of the cutouts, which are split into two balanced data sets with ‘true’ and ‘false’ point-like source candidates. We tested our CNN model on the candidates produced by two different transient detection pipelines. In addition, we made use of several diagnostic tools to evaluate the classification performance of our CNN models. Results. We show that our CNN algorithm can be successfully trained on a large and diverse array of images on very different pixel scales. In this training process, we did not detect any strong over- or underfitting with the requirement of providing cutouts with a limited size no larger than 50 × 50 pixels. Tested on optical images from four different telescopes and utilising two different transient detection pipelines, our CNN model provides a robust ‘real or bogus’ classification performance accuracy from 93% up to 98% for well-classified candidates. © K. Makhlouf et al. 2022., D.T. is funded by the CNES Postdoctoral Fellowship program at the CEA-Saclay/AIM/Irfu laboratory. S.K. acknowledges 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-CTA-N operation is supported by the Czech Ministry of Education, Youth and Sports (projects LM2015046, LM2018105, LTT17006) and by European Structural and Investment Fund and the Czech Ministry of Education, Youth and Sports (projects CZ.02.1.01/0.0/0.0/16_013/0001403 and CZ.02.1.01/0.0/0.0/18_046/0016007). D.A.K. acknowledges supportfrom SpanishNational ResearchProjectRTI2018-098104-J-I00 (GRBPhot). This research has made use of the VizieR catalogue access tool, CDS, Strasbourg, France. The authors warmly thank the GRANDMA Collaboration for providing images taken from their optical follow-up of gravitational wave sources during the O3 run., With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709.

Full list of authors: Agüı́ Fernández, J. F.; Thone, C. C.; Kann, D. A.; Postigo, A. de Ugarte; Selsing, J.; Schady, P.; Yates, R. M.; Greiner, J.; Oates, S. R.; Malesani, D. B.; Xu, D.; Klotz, A.; Campana, S.; Rossi, A.; Perley, D. A.; Blazek, M.; D'Avanzo, P.; Giunta, A.; Hartmann, D.; Heintz, K. E.; Jakobsson, P.; Kirkpatrick, C. C., IV; Kouveliotou, C.; Melandri, A.; Pugliese, G.; Salvaterra, R.; Starling, R. L. C.; Tanvir, N. R.; Vergani, S. D.; Wiersema, K., Short gamma-ray bursts (SGRBs) are produced by the coalescence of compact binary systems which are remnants of massive stars. GRB 160410A is classified as a short-duration GRB with extended emission and is currently the farthest SGRB with a redshift determined from an afterglow spectrum and also one of the brightest SGRBs to date. The fast reaction to the Neil Gehrels Swift Observatory alert allowed us to obtain a spectrum of the afterglow using the X-shooter spectrograph at the Very Large Telescope (VLT). The spectrum shows several absorption features at a redshift of z = 1.7177, in addition, we detect two intervening systems at z = 1.581 and z = 1.444. The spectrum shows Ly α in absorption with a column density of log (N(H I)/cm2) = 21.2 ± 0.2 which, together with Fe II, C II, Si II, Al II, and O I, allow us to perform the first study of chemical abundances in a SGRB host galaxy. We determine a metallicity of [X/H] = −2.3 ± 0.2 for Fe II and −2.5 ± 0.2 for Si II and no dust depletion. We also find no evidence for extinction in the afterglow spectral energy distribution modelling. The environment has a low degree of ionization and the C IV and Si IV lines are completely absent. We do not detect an underlying host galaxy down to deep limits. Additionally, we compare GRB 160410A to GRB 201221D, another high-z short GRB that shows absorption lines at z = 1.045 and an underlying massive host galaxy. © 2023 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society., JFAF acknowledges support from the Spanish Ministerio de Ciencia, Innovación y Universidades through the grant PRE2018-086507. DAK and JFAF acknowledge support from Spanish National Research Project RTI2018-098104-J-I00 (GRBPhot). AdUP acknowledges funding from a Ramón y Cajal fellowship (RyC-2012-09975). MB acknowledges funding associated to a personal tecnico de apoyo fellowship (PTA2016-13192-I). DBM acknowledges research grant 19054 from VILLUM FONDEN. Part of the funding for Gamma-Ray burst Optical and Near-infrared Detector (GROND) (both hardware as well as personnel) was generously granted from the Leibniz Prize to Prof. G. Hasinger (DFG grant HA 1850/28-1). AR acknowledges support from the Istituto Nazionale di Astrofisica (INAF) project Premiale Supporto Arizona & Italia., With funding from the Spanish government through the "Severo Ochoa Centre of Excellence" accreditation (CEX2021-001131-S).

The Transiting Exoplanet Survey Satellite (TESS) exoplanet-hunting mission detected the rising and decaying optical afterglow of GRB 191016A, a long gamma-ray burst (GRB) detected by Swift-BAT but without prompt XRT or UVOT follow-up due to proximity to the Moon. The afterglow has a late peak at least 1000 s after the BAT trigger, with a brightest-detected TESS data point at 2589.7 s post-Trigger. The burst was not detected by Fermi-LAT, but was detected by Fermi-GBM without triggering, possibly due to the gradual nature of the rising light curve. Using ground-based photometry, we estimate a photometric redshift of zphot = 3.29 ± 0.40. Combined with the high-energy emission and optical peak time derived from TESS, estimates of the bulk Lorentz factor ?BL range from 90 to 133. The burst is relatively bright, with a peak optical magnitude in ground-based follow-up of R = 15.1 mag. Using published distributions of GRB afterglows and considering the TESS sensitivity and sampling, we estimate that TESS is likely to detect ∼1 GRB afterglow per year above its magnitude limit. © 2021 Institute of Physics Publishing. All rights reserved., Support for K.L.S. was provided by the National Aeronautics and Space Administration through Einstein Postdoctoral Fellowship Award Number PF7-180168, issued by the Chandra X-ray Observatory Center, which is operated by the Smithsonian Astrophysical Observatory for and on behalf of the National and Aeronautics Space Administration under contract NAS8-03060. P.V. acknowledges support from NASA grants 80NSSC19K0595 and NNM11AA01A. This paper includes data collected by the TESS mission. D.A.K. acknowledges support from Spanish National Research Project RTI2018-098104-J-I00 (GRBPhot). Z.R.W. acknowledges support through NASA grant 80NSSC19K1731. Funding for the TESS mission is provided by the NASA Explorer Program. This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/consortium).Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. The Digitized Sky Survey was produced at the Space Telescope Science Institute under U.S. Government grant NAG W-2166. The images of these surveys are based on photographic data obtained using the Oschin Schmidt Telescope on Palomar Mountain and the UK Schmidt Telescope. The plates were processed into the present compressed digital form with the permission of these institutions., With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709.

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited., Gamma-ray bursts (GRBs) are classified into long and short events. Long GRBs (LGRBs) are associated with the end states of very massive stars, while short GRBs (SGRBs) are linked to the merger of compact objects. GRB 200826A was a peculiar event, because by definition it was an SGRB, with a rest-frame duration of ∼0.5 s. However, this event was energetic and soft, which is consistent with LGRBs. The relatively low redshift (z = 0.7486) motivated a comprehensive, multiwavelength follow-up campaign to characterize its host, search for a possible associated supernova (SN), and thus understand the origin of this burst. To this aim we obtained a combination of deep near-infrared (NIR) and optical imaging together with spectroscopy. Our analysis reveals an optical and NIR bump in the light curve whose luminosity and evolution are in agreement with several SNe associated to LGRBs. Analysis of the prompt GRB shows that this event follows the Ep,i–Eiso relation found for LGRBs. The host galaxy is a low-mass star-forming galaxy, typical of LGRBs, but with one of the highest star formation rates, especially with respect to its mass ($\mathrm{log}{M}_{* }/{M}_{\odot }=8.6$, SFR ∼ 4.0 M⊙ yr−1). We conclude that GRB 200826A is a typical collapsar event in the low tail of the duration distribution of LGRBs. These findings support theoretical predictions that events produced by collapsars can be as short as 0.5 s in the host frame and further confirm that duration alone is not an efficient discriminator for the progenitor class of a GRB. © 2022. The Author(s). Published by the American Astronomical Society., A.R. acknowledges support from the INAF project Premiale Supporto Arizona & Italia. B.R. would like to acknowledge the assistance and support of R. T. Gatto. D.A.K. acknowledges support from Spanish National Research Project RTI2018-098104-J-I00 (GRBPhot). P.D'A. acknowledges funding from the Italian Space Agency, contract ASI/INAF No. I/004/11/4. L.I. was supported by two grants from VILLUM FONDEN (project No. 16599 and 25501). A.N.G. and S.K. acknowledge financial support from grants DFG Kl 766/16-3, DFG Kl 766/18-1, and DFG RA 2484/1-3. A.N.G. acknowledges support from Thüringer Landessternwarte Tautenburg. A.S.P., P.Y.M., and A.A.V. acknowledge support from RSF grant 18-12-00378. S.S. acknowledges support from the G.R.E.A.T. research environment, funded by Vetenskapsrådet, the Swedish Research Council, project No. 2016-06012. A.R., E.Pi., P.D'A., L.A., A.P., E.Pa., S.S., G.S., S.C., V.D'E., M.D.V., and A.M. acknowledge support from PRIN-MIUR 2017 (grant 20179ZF5KS). The LBT is an international collaboration among institutions in the United States, Italy, and Germany. The LBT Corporation partners are the University of Arizona on behalf of the Arizona Board of Regents; Istituto Nazionale di Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, the Leibniz Institute for Astrophysics Potsdam, and Heidelberg University; and the Ohio State University, representing OSU, University of Notre Dame, University of Minnesota, and University of Virginia. This work made use of data supplied by the UK Swift Science Data Centre at the University of Leicester., With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709.

The hosts of long duration gamma-ray bursts (GRBs) are predominantly starburst galaxies at subsolar metallicity. At redshifts z < 1, this implies that most of them are low-mass galaxies similar to the populations of blue compact dwarfs and dwarf irregulars. What triggers the massive star-formation needed for producing a GRB progenitor is still largely unknown, as are the resolved gas properties and kinematics of these galaxies and their formation history. Here we present a sample of six spatially resolved GRB hosts at z < 0.3 observed with 3D spectroscopy at high spectral resolution (R = 8000-13 000) using FLAMES/VLT. We analyzed the resolved gas kinematics of the full sample and the abundances in a subsample with strong enough emission lines. Only two galaxies show a regular disk-like rotation field, another two are dispersion-dominated, and the remaining ones have two narrow emission components associated with different parts of the galaxy but no regular rotation field, which might indicate a recent merger. All galaxies show evidence for broad components underlying the main emission peak with σ of 50-110 km s-1. This broad component is more metal-rich than the narrow components, it is blueshifted in most cases, and it follows a different velocity structure. We find a weak correlation between the star-formation rate and the width of the broad component, its flux compared to the narrow component, and the maximum outflow velocity of the gas, but we do not find any correlation with the star-formation density, metallicity or stellar mass. We hence associate this broad component with a metal-rich outflow from star-forming regions in the host. The GRB is not located in the brightest region of the host, but is always associated with some star-forming region showing a clear wind component. Our study shows the great potential of 3D spectroscopy to study the star-formation processes and history in galaxies hosting extreme transients, the need for high signal-To-noise, and the perils using unresolved or only partially resolved data for these kinds of studies. © ESO 2021., CT and AdUP acknowledge support from AYA2017-89384-P, CT and AdUP also from a Ramón y Cajal fellowships RyC-2012-09984 and RyC-2012-09975, LI from a Juan de la Cierva Integración fellowship IJCI-2016-30940. DAK acknowledges support from the Spanish National Research Project RTI2018-098104-J-I00 (GRBPhot). JFAF acknowledges support from the Spanish Ministerio de Ciencia, Innovación y Universidades through the grant PRE2018-086507. SDV acknowledges support from the French National Research Agency (ANR) under contract ANR-16-CE31-0003. LC is supported by YDUN grant DFF 4090-00079. Ground based observations were collected at the VLT under program 092.D-0389(A)., With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709.

We investigate the shape of the jet break in within-beam gamma-ray burst (GRB) optical afterglows for various lateral jet structure profiles. We consider cases with and without lateral spreading and a range of inclinations within the jet core half-opening angle, θc. We fit model and observed afterglow light curves with a smoothly-broken power-law function with a free-parameter κ that describes the sharpness of the break. We find that the jet break is sharper (κ is greater) when lateral spreading is included than in the absence of lateral spreading. For profiles with a sharp-edged core, the sharpness parameter has a broad range of 0.1 ≤ κ ≤ 4.6, whereas profiles with a smooth-edged core have a narrower range of 0.1 ≤ κ ≤ 2.2 when models both with and without lateral spreading are included. For sharp-edged jets, the jet break sharpness depends strongly on the inclination of the system within θc, whereas for smooth-edged jets, κ is more strongly dependent on the size of θc. Using a sample of 20 GRBs, we find 9 candidate smooth-edged jet structures and 8 candidate sharp-edged jet structures, while the remaining 3 are consistent with either. The shape of the jet break, as measured by the sharpness parameter κ, can be used as an initial check for the presence of lateral structure in within-beam GRBs where the afterglow is well-sampled at and around the jet-break time. © 2021 The Author(s)., GPL and JJF thank Shiho Kobayashi for useful discussions and comments on a pre-submission version. GPL thanks Lekshmi Resmi for valuable discussions. GPL is supported by the Science Technology and Facilities Council (STFC) via grant ST/S000453/1. DAK acknowledges support from Spanish National Research Project RTI2018-098104-J-I00 (GRBPhot), and thanks S. Schulze and M. Blažek for calculations support. IM is a recipient of the Australian Research Council Future Fellowship FT190100574., With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709.

Wide-angle surveys at different wavelengths are already providing triggers for very different kinds of transients. The most interesting science is produced when new sources are followed-up and characterised by using the right instrumentation, telescopes and observing strategies. In the coming years, with new large-scale surveys such as ZTF and LSST, the amount of triggers is expected to scale up massively. Furthermore, new observational windows, such as gravitational waves or neutrinos, are now opening and adding complexity to the picture. The instrumentation and strategies that we have been using over recent years may just not be appropriate for those new situations. In this Workshop we discussed the present and projected future of transient discovery, the instrumentation that will be needed for the follow-up of those targets, and the observing strategies, data analysis and community efforts that will be required to tackle the challenges that lie ahead of us.

Context. For the first time, very high energy emission up to the TeV range has been reported for a gamma-ray burst (GRB). It is still unclear whether the environmental properties of GRB 190114C might have contributed to the production of these very high energy photons, or if it is solely related to the released GRB emission. Aims. The relatively low redshift of the GRB (z = 0.425) allows us to study the host galaxy of this event in detail, and to potentially identify idiosyncrasies that could point to progenitor characteristics or environmental properties that might be responsible for this unique event. Methods. We used ultraviolet, optical, infrared, and submillimetre imaging and spectroscopy obtained with the HST, the VLT, and ALMA to obtain an extensive dataset on which the analysis of the host galaxy is based. Results. The host system is composed of a close pair of interacting galaxies (Δv = 50 km s-1), both of which are well detected by ALMA in CO(3-2). The GRB occurred within the nuclear region (∼170 pc from the centre) of the less massive but more star-forming galaxy of the pair. The host is more massive (log(M/M⊙ ) = 9.3) than average GRB hosts at this redshift, and the location of the GRB is rather unique. The higher star formation rate was probably triggered by tidal interactions between the two galaxies. Our ALMA observations indicate that both host galaxy and companion have a high molecular gas fraction, as has been observed before in interacting galaxy pairs. Conclusions. The location of the GRB within the core of an interacting galaxy with an extinguished line of sight is indicative of a denser environment than typically observed for GRBs and could have been crucial for the generation of the very high energy photons that were observed. © ESO 2020., This paper makes use of the following ALMA data: ADS/JAO.ALMA#2018.A.00020.T. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), MOST and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ. CT, AdUP, DAK, MB, and LI acknowledge support from the Spanish research project AYA2017-89384-P. CT and AdUP acknowledge support from funding associated to Ramon y Cajal fellowships (RyC-2012-09984 and RyC-2012-09975). DAK acknowledges support from the Spanish research project RTI2018-098104-J-I00. M.J.M. acknowledges the support of the National Science Centre, Poland through the SONATA BIS grant 2018/30/E/ST9/00208. JPUF thanks the Carlsberg Foundation for support. KEH and PJ acknowledge support by a Project Grant (162948-051) from The Icelandic Research Fund. JS and DW are supported in part by Independent Research Fund Denmark grant DFF-7014-00017. The Cosmic Dawn Center is supported by the Danish National Research Foundation under grant No. 140.

Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. T.P. acknowledges support from NASA under the Swift GI grant 1619152, the Tess GI grant G03267, from the NYU Center for Cosmology and Particle Physics, from a 19 Washington Square North Award awarded to M.M, and in part by a grant from the New York University Research Challenge FundProgram. M.M. and the SNYU group have been supported by the NSF CAREER award AST-1352405, by the NSF award AST1413260, and by a Humboldt Faculty Fellowship. M.M. is grateful for her sabbatical stay supported by the Center for Computational Astrophysics at the Flatiron institute and for the hospitality of the Max-Planck Institute for Astronomy, Heidelberg, during which some of this work was accomplished. K.B. acknowledges financial support from the Ministerio de Economia y Competitividad through the Spanish grant BES2014-069767. K.B., C.T. and A.d.U.P. acknowledge support from the Spanish research project AYA2017-89384-P. C.T. acknowledges support from funding associated to a Ramon y Cajal fellowship RyC-2012-09984. A.d.U.P. acknowledges support from funding associated to a Ramon y Cajal fellowship RyC-2012-09975. L.I. acknowledges support from funding associated to a Juan de la Cierva Incorporacion fellowship IJCI-2016-30940. D.A.K. acknowledges support from the Spanish research projects AYA 2014-58381-P, AYA201789384-P, from Juan de la Cierva Incorporacion fellowship IJCI-2015-26153, and from Spanish National Project research project RTI2018-098104-J-I00 (GRBPhot). J.V. and his research group at Konkoly Observatory is supported by the "Transient Astrophysical Objects" GINOP 2.3.2-15-2016-00033 project of the National Research, Development and Innovation Office (NKFIH), Hungary, funded by the European Union. K.V. and L.K. thank the financial support from the National Research, Development and Innovation Office (NKFIH), Hungary, under grants NKFI-K-131508 and NKFI-KH-130526. A.B. and K.V. are supported by the Lendulet program grant LP2018-7/2019 of the Hungarian Academy of Sciences. T.N.D. also acknowledges the support of the Hungarian OTKA grant No. 119993. The work of X.W. was funded by the National Science Foundation of China (NSFC grants 12033003, 11633002, and 11761141001), the Major State Basic Research Development Program (grant No. 2016YFA0400803), and the Scholar Program of Beijing Academy of Science and Technology (DZ:BS202002). L.G. was funded by the European Union's Horizon 2020 research and innovation program under the Marie SklodowskaCurie grant agreement No. 839090. This work has been partially supported by the Spanish grant PGC2018-095317-BC21 within the European Funds for Regional Development (FEDER). R.G.B. acknowledges financial support from the Spanish Ministry of Economy and Competitiveness through grant AYA2016-77846-P and from the State Agency for Research of the Spanish MCIU through the "Center of Excellence Severo Ochoa" award to the Instituto de Astrofisica de Andalucia (SEV-2017-0709). These observations made use of the LCO network. D.A.H., C.P., D.H., and J.B. are supported by NSF Grant AST-1911225 and NASA Grant 80NSSC19k1639., In the last decade a number of rapidly evolving transients have been discovered that are not easily explained by traditional supernova models. We present optical and UV data on one such object, SN 2018gep, that displayed a fast rise with a mostly featureless blue continuum around peak, and evolved to develop broad features typical of an SN Ic-bl while retaining significant amounts of blue flux throughout its observations. This blue excess is most evident in its near-UV flux, which is over 4 mag brighter than other stripped-envelope supernovae, and is still visible in optical g-r colors. Its fast rise time of t (rise,V ) = 5.6 +/- 0.5 days puts it squarely in the emerging class of Fast Evolving Luminous Transients, or Fast Blue Optical Transients. With a peak absolute magnitude of M ( v ) = -19.53 +/- 0.23 mag it is on the extreme end of both the rise time and peak magnitude distribution for SNe Ic-bl. These observations are consistent with a simple SN Ic-bl model that has an additional form of energy injection at early times that drives the observed rapid, blue rise. We show that SN 2018gep and the literature SN iPTF16asu have similar photometric and spectroscopic properties and that they overall share many similarities with both SNe Ic-bl and Fast Evolving Transients. Based on our SN 2018gep host galaxy data we derive a number of properties, and we show that the derived host galaxy properties for both SN 2018gep and iPTF16asu are consistent with the SNe Ic-bl and gamma-ray burst/supernova sample while being on the extreme edge of the observed Fast Evolving Transient sample., W.M. Keck Foundation, NASA under the Swift GI grant 1619152, Tess GI grant G03267, NYU Center for Cosmology and Particle Physics, New York University Research Challenge FundProgram, National Science Foundation (NSF) NSF - Office of the Director (OD) AST-1352405 National Science Foundation (NSF) AST-1911225 AST-1413260, Humboldt Faculty Fellowship, Center for Computational Astrophysics at the Flatiron institute, Spanish Government BES2014-069767 RyC-2012-09975 RyC-2012-09984, Juan de la Cierva Incorporacion fellowship IJCI-2015-26153 IJCI-2016-30940, "Transient Astrophysical Objects" project of the National Research, Development and Innovation Office (NKFIH), Hungary - European Union GINOP 2.3.2-15-2016-00033, National Research, Development & Innovation Office (NRDIO) - Hungary NKFI-K-131508 NKFI-KH-130526, Hungarian Academy of Sciences LP2018-7/2019, Orszagos Tudomanyos Kutatasi Alapprogramok (OTKA) 119993, National Natural Science Foundation of China (NSFC) 12033003 11633002 11761141001, National Basic Research Program of China 2016YFA0400803, Scholar Program of Beijing Academy of Science and Technology DZ:BS202002, European Commission 839090 PGC2018-095317-BC21, Spanish Ministry of Economy and Competitiveness AYA2016-77846-P, State Agency for Research of the Spanish MCIU through the "Center of Excellence Severo Ochoa" award SEV-2017-0709, National Aeronautics & Space Administration (NASA) 80NSSC19k1639, 19 Washington Square North Award AYA 2014-58381-P AYA201789384-P RTI2018-098104-J-I00 AYA2017-89384-P

We present the results of the monitoring campaign of the Type IIn supernova (SN) 2018cnf (a.k.a. ASASSN-18mr). It was discovered about ten days before the maximum light (on MJD = 58 293.4 ± 5.7 in the V band, with MV = ?18.13 ± 0.15 mag). The multiband light curves show an immediate post-peak decline with some minor luminosity fluctuations, followed by a flattening starting about 40 days after maximum. The early spectra are relatively blue and show narrow Balmer lines with P Cygni profiles. Additionally, Fe II, O I, He I, and Ca II are detected. The spectra show little evolution with time and with intermediate-width features becoming progressively more prominent, indicating stronger interaction of the SN ejecta with the circumstellar medium. The inspection of archival images from the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) survey has revealed a variable source at the SN position with a brightest detection in December 2015 at Mr = ?14.66 ± 0.17 mag. This was likely an eruptive phase from the massive progenitor star that started from at least mid-2011, and that produced the circumstellar environment within which the star exploded as a Type IIn SN. The overall properties of SN 2018cnf closely resemble those of transients such as SN 2009ip. This similarity favours a massive hypergiant, perhaps a luminous blue variable, as progenitor for SN 2018cnf. © ESO 2019, We thank the anonymous referee for insightful comments that helped to improve the paper. D.A.H, C.M., and G.H. were supported by NSF grant AST-1313484. S.B., P.C., and S.D. acknowledge Project 11573003 supported by NSFC. This research uses data obtained through the Telescope Access Program (TAP), which has been funded by the National Astronomical Observatories of China, the Chinese Academy of Sciences, and the Special Fund for Astronomy from the Ministry of Finance. M.G. is supported by the Polish National Science Centre grant OPUS 2015/17/B/ST9/03167. T.W. is funded in part by European Research Council grant 320360 and by European Commission grant 730980. E.Y.H., C.A., and S.K. acknowledge the support provided by the National Science Foundation under Grant No. AST-1613472. M.F. is supported by a Royal Society -Science Foundation Ireland University Research Fellowship. M.M.P. acknowledges support from the National Science Foundation under grants AST-1008343 and AST-1613426. C.T., A.dU.P., D.A.K., and L.I. acknowledge support from the Spanish research project AYA2017-89384-P.C.T. and A.dU.P. acknowledge support from funding associated to Ramon y Cajal fellowships (RyC-2012-09984 and RyC-2012-09975). D.A.K. and L.I. acknowledge support from funding associated to Juan de la Cierva Incorporacion fellowships (IJCI-2015-26153 and IJCI-2016-30940). G.P and O.R. acknowledge support by the Ministry of Economy, Development, and Tourism's Millennium Science Initiative through grant IC120009, awarded to The Millennium Institute of Astrophysics, MAS. L. W. is sponsored, in part, by the Chinese Academy of Sciences (CAS), through a grant to the CAS South America Center for Astronomy (CASSACA) in Santiago, Chile. The NOT data were obtained through the NOT Unbiased Transient Survey (NUTS; http://csp2.lco.cl/not/), which is supported in part by the Instrument Center for Danish Astrophysics (IDA). This work is based, in part, on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile, under ESO programme 0101. D-0202, and as part of PESSTO (the Public ESO Spectroscopic Survey for Transient Objects Survey) ESO program 188. D-3003, 191. D-0935, 197. D-1075. This work also makes use of data from the Las Cumbres Observatory Network as part of the Global Supernova Project; the Nordic Optical Telescope (NOT), operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias; the 1.82m Copernico Telescope of INAF-Asiago Observatory; the Gran Telescopio Canarias (GTC), installed in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias, in the Island of La Palma; the 6.5m Magellan Telescopes located at Las Campanas Observatory, Chile; and the Liverpool Telescope operated on the island of La Palma by Liverpool John Moores University at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias with financial support from the UK Science and Technology Facilities Council. It is also based in part on observations at Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory (NOAO), which is operated by the Association of Universities for Research in Astronomy (AURA), Inc. under a cooperative agreement with the National Science Foundation. ASAS-SN is supported by the Gordon and Betty Moore Foundation through grant GBMF5490 to the Ohio State University and NSF grant AST-1515927. Development of ASAS-SN has been supported by NSF grant AST0908816, the Mt. Cuba Astronomical Foundation, the Center for Cosmology and AstroParticle Physics at the Ohio State University, the Chinese Academy of Sciences South America Center for Astronomy (CAS-SACA), the Villum Foundation, and George Skestos. The Pan-STARRS1 Surveys (PS1) have been made possible through contributions of the Institute for Astronomy, the University of Hawaii, the Pan-STARRS Project Office, the Max-Planck Society and its participating institutes, the Max Planck Institute for Astronomy, Heidelberg, and the Max Planck Institute for Extraterrestrial Physics, Garching, The Johns Hopkins University, Durham University, the University of Edinburgh, Queen's University Belfast, the Harvard-Smithsonian Center for Astrophysics, the Las Cumbres Observatory Global Telescope Network Incorporated, the National Central University of Taiwan, STScI, NASA under Grant No. NNX08AR22G issued through the Planetary Science Division of the NASA Science Mission Directorate, the US NSF under Grant No. AST-1238877, the University of Maryland, and Eotvos Lorand University (ELTE), the Los Alamos National Laboratory, and the Gordon and Betty Moore Foundation. This research has made use of the NASA-IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

The low distance, $z=0.0591$, of GRB 100316D and its association with SN 2010bh represent two important motivations for studying this host galaxy and the GRB's immediate environment with the Integral-Field Spectrographs like VLT/MUSE. Its large field-of-view allows us to create 2D maps of gas metallicity, ionization level, and the star-formation rate distribution maps, as well as to investigate the presence of possible host companions. The host is a late-type dwarf irregular galaxy with multiple star-forming regions and an extended central region with signatures of on-going shock interactions. The GRB site is characterized by the lowest metallicity, the highest star-formation rate and the youngest ($\sim$ 20-30 Myr) stellar population in the galaxy, which suggest a GRB progenitor stellar population with masses up to 20 -- 40 $M_{\odot}$. We note that the GRB site has an offset of $\sim$660pc from the most luminous SF region in the host. The observed SF activity in this galaxy may have been triggered by a relatively recent gravitational encounter between the host and a small undetected ($L_{H\alpha} \leq 10^{36}$ erg/s) companion., Comment: 19 pages, 17 figures, 6 tables. Updated version after referee comments. Accepted for publication in MNRAS

Full list of authors: Misra, K.; Resmi, L.; Kann, D. A.; Marongiu, M.; Moin, A.; Klose, S.; Bernardi, G.; de Ugarte Postigo, A.; Jaiswal, V. K.; Schulze, S.; Perley, D. A.; Ghosh, A.; Dimple; Kumar, H.; Gupta, R.; Michałowski, M. J.; Martín, S.; Cockeram, A.; Cherukuri, S. V.; Bhalerao, V.; Anderson, G. E.; Pandey, S. B.; Anupama, G. C.; Thöne, C. C.; Barway, S.; Wieringa, M. H.; Fynbo, J. P. U.; Habeeb, N., We present radio and optical afterglow observations of the TeV-bright long gamma-ray burst 190114C at a redshift of z = 0.425, which was detected by the Major Atmospheric Gamma Imaging Cherenkov telescope. Our observations with Atacama Large Millimeter/submillitmeter Array, Australia Telescope Compact Array, and upgraded Giant Metre-wave Radio Telescope were obtained by our low frequency observing campaign and range from ∼1 to ∼140 d after the burst and the optical observations were done with three optical telescopes spanning up to ∼25 d after the burst. Long-term radio/mm observations reveal the complex nature of the afterglow, which does not follow the spectral and temporal closure relations expected from the standard afterglow model. We find that the microphysical parameters of the external forward shock, representing the share of shock-created energy in the non-thermal electron population and magnetic field, are evolving with time. The inferred kinetic energy in the blast-wave depends strongly on the assumed ambient medium density profile, with a constant density medium demanding almost an order of magnitude higher energy than in the prompt emission, while a stellar wind-driven medium requires approximately the same amount energy as in prompt emission. © 2021 The Author(s)., We thank the staff of the GMRT that made these observations possible. GMRT is run by the National Centre for Radio Astrophysics (NCRA) of the Tata Institute of Fundamental Research (TIFR). This paper makes use of the following ALMA data: ADS/JAO.ALMA#2018.1.01410.T, ADS/JAO.ALMA#2018.A.00020.T. ALMA is a partnership of ESO (representing its member states), NSF (USA), and NINS (Japan), together with NRC (Canada), MOST and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ. The Australia Telescope Compact Array (ATCA) is part of the Australia Telescope National Facility which is funded by the Australian Government for operation as a National Facility managed by CSIRO. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. We thank Gaurav Waratkar, Viraj Karambelkar, and Shubham Srivastava for undertaking the optical observations with the GIT. The GIT is a 70 cm telescope with a 0.7 deg field of view, set up by the Indian Institute of Astrophysics (IIA, Bengaluru) and the Indian Institute of Technology Bombay (IITB) with support from the Indo-US Science and Technology Forum (IUSSTF) and the Science and Engineering Research Board (SERB) of the Department of Science and Technology (DST), Government of India (https://sites.google.com/view/growthindia/). It is located at the Indian Astronomical Observatory (Hanle), operated by the Indian Institute of Astrophysics (IIA). This work made use of data supplied by the UK Swift Science Data Centre at the University of Leicester. LR and VKJ acknowledge support from the grant EMR/2016/007127 from Dept. of Science and Technology, India. DAK, AdUP, and CCT acknowledge support from the Spanish research project AYA2017-89384-P. AdUP and CT acknowledge support from funding associated to Ramón y Cajal fellowships (RyC-2012-09975 and RyC-2012-09984). DAK also acknowledges support from the Spanish research project RTI2018-098104-J-I00 (GRBPhot). KM, SBP, and RG acknowledge BRICS grant DST/IMRCD/BRICS/Pilotcall/ProFCheap/2017(G) for this work. V. Jaiswal and S. V. Cherukuri thank Ishwara-Chandra C. H. for kindly making GMRT data analysis pipeline available. L Resmi thanks Johannes Buchner for helpful discussions on pyMultinest. Harsh Kumar thanks the LSSTC Data Science Fellowship Program, which is funded by LSSTC, NSF Cybertraining Grant #1829740, the Brinson Foundation, and the Moore Foundation; his participation in the program has benefited this work. The Cosmic Dawn Center is funded by the DNRF. JPUF thanks the Carlsberg Foundation for support. MJM acknowledges the support of the National Science Centre, Poland through the SONATA BIS grant 2018/30/E/ST9/00208. GEA is the recipient of an Australian Research Council Discovery Early Career Researcher Award (project number DE180100346) funded by the Australian Government., With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709.

Long γ-ray bursts are associated with energetic, broad-lined, stripped-envelope supernovae and as such mark the death of massive stars. The scarcity of such events nearby and the brightness of the γ-ray burst afterglow, which dominates the emission in the first few days after the burst, have so far prevented the study of the very early evolution of supernovae associated with γ-ray bursts. In hydrogen-stripped supernovae that are not associated with γ-ray bursts, an excess of high-velocity (roughly 30,000 kilometres per second) material has been interpreted as a signature of a choked jet, which did not emerge from the progenitor star and instead deposited all of its energy in a thermal cocoon. Here we report multi-epoch spectroscopic observations of the supernova SN 2017iuk, which is associated with the γ-ray burst GRB 171205A. Our spectra display features at extremely high expansion velocities (around 115,000 kilometres per second) within the first day after the burst. Using spectral synthesis models developed for SN 2017iuk, we show that these features are characterized by chemical abundances that differ from those observed in the ejecta of SN 2017iuk at later times. We further show that the high-velocity features originate from the mildly relativistic hot cocoon that is generated by an ultra-relativistic jet within the γ-ray burst expanding and decelerating into the medium that surrounds the progenitor star. This cocoon rapidly becomes transparent and is outshone by the supernova emission, which starts to dominate the emission three days after the burst. © 2019, Springer Nature Limited., L.I. acknowledges support from funding associated with Juan de la Cierva Incorporacion fellowship IJCI-2016-30940. L.I., A.d.U.P., C.C.T. and D.A.K. acknowledge support from the Spanish research project AYA2017-89384-P. A.d.U.P. acknowledges support from funding associated with Ramon y Cajal fellowship RyC-2012-09975. C.C.T. acknowledges support from funding associated with Ramon y Cajal fellowship RyC-2012-09984. D.A.K. acknowledges support from funding associated with Juan de la Cierva Incorporacion fellowship IJCI-2015-26153. K.M. acknowledges support from JSPS Kakenhi grants (18H05223, 18H04585 and 17H02864). S. Schmidl acknowledges support from grant DFG Klose 766/16-3 and discussions with S. Klose. R.L.C.S. acknowledges funding from STFC. M.J.M. acknowledges the support of the National Science Centre, Poland, through POLONEZ grant 2015/19/P/ST9/04010; this project has received funding from the European Union's Horizon 2020 research and innovation programme under Marie Sklodowska-Curie grant agreement number 665778. R.S.-R. acknowledges support from ASI (Italian Space Agency) through contract number 2015-046-R.0 and from the European Union's Horizon 2020 programme under the AHEAD project (grant agreement number 654215). The Cosmic Dawn Center is funded by the DNRF. J.H. was supported by a VILLUM FONDEN Investigator grant (project number 16599). G.L. was supported by a research grant from VILLUM FONDEN (project number 19054). K.E.H. acknowledges support by a Project Grant (162948-051) from The Icelandic Research fund. J.J. and L.K. acknowledge support from NOVA and NWO-FAPESP grant for advanced instrumentation in astronomy.

Context. Long gamma-ray bursts (GRBs) are produced during the dramatic deaths of massive stars with very short lifetimes, meaning that they explode close to the birth place of their progenitors. Over a short period they become the most luminous objects observable in the Universe, being perfect beacons to study high-redshift star-forming regions. Aims. We aim to use the afterglow of GRB 161023A at a redshift z = 2.710 as a background source to study the environment of the explosion and the intervening systems along its line of sight. Methods. For the first time, we complement ultraviolet (UV), optical and near-infrared (NIR) spectroscopy with millimetre spectroscopy using the Atacama Large Millimeter Array (ALMA), which allows us to probe the molecular content of the host galaxy. The X-shooter spectrum shows a plethora of absorption features including fine-structure and metastable transitions of Fe, Ni, Si, C, and O. We present photometry ranging from 43 s to over 500 days after the burst. Results. We infer a host-galaxy metallicity of [Zn/H] = -1.11 ± 0.07, which, corrected for dust depletion, results in [X/H] = -0.94 ± 0.08. We do not detect molecular features in the ALMA data, but we derive limits on the molecular content of log(N/cm) < 15.7 and log(N/cm, which are consistent with those that we obtain from the optical spectra, log(N/cm)< 15.2 and log(N/cm) < 14.5. Within the host galaxy, we detect three velocity systems through UV, optical and NIR absorption spectroscopy, all with levels that were excited by the GRB afterglow. We determine the distance from these systems to the GRB to be in the range between 0.7 and 1.0 kpc. The sight line to GRB 161023A shows nine independent intervening systems, most of them with multiple components. Conclusions. Although no molecular absorption was detected for GRB 161023A, we show that GRB millimetre spectroscopy is now feasible and is opening a new window on the study of molecular gas within star-forming galaxies at all redshifts. The most favoured lines of sight for this purpose will be those with high metallicity and dust.© ESO 2018., AdUP and CT acknowledge support from Ramon y Cajal fellowships RyC-2012-09975 and RyC-2012-09984 and the Spanish Ministry of Economy and Competitiveness through projects AYA2014-58381-P and AYA2017-89384-P, AdUP furthermore from the BBVA foundation. DAK acknowledges support from the Spanish research project AYA 2014-58381-P, and from Juan de la Cierva Incorporacion fellowship IJCI-2015-26153. FEB acknowledges support from CONICYT-Chile (Basal-CATA PFB-06/2007) and the Ministry of Economy, Development, and Tourism's Millennium Science Initiative through grant IC120009, awarded to The Millennium Institute of Astrophysics, MAS. Part of the funding for GROND (both hardware as well as personnel) was generously granted from the Leibniz-Prize to Prof. G. Hasinger (DFG grant HA 1850/28-1). JB acknowledges support through the Sofja Kovalevskaja Award to P. Schady from the Alexander von Humboldt Foundation of Germany. MJM acknowledges the support of the National Science Centre, Poland through the POLONEZ grant 2015/19/P/ST9/04010; this project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 665778. AG acknowledges the financial support from the Slovenian Research Agency (research core funding No. P1-0031 and project grant No. J1-8136) and networking support by the COST Action GWverse CA16104. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programmes 098.A-0055, 098.D-0710 and 0100.D-0649. This paper makes use of the following ALMA data: ADS/JAO.ALMA#2016.1.00862. T. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada) and NSC and ASIAA (Taiwan) and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ. This work is based in part on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. Support for this work was provided by NASA through an award issued by JPL/Caltech.

The spectacular success of Type Ia supernovae (SNe Ia) in SN-cosmology is based on the assumption that their photometric and spectroscopic properties are invariant with redshift. However, this fundamental assumption needs to be tested with observations of high-z SNe Ia. To date, the majority of SNe Ia observed at moderate to large redshifts (0.4 ≤ z ≤ 1.0) are faint, and the resultant analyses are based on observations with modest signal-to-noise ratios that impart a degree of ambiguity in their determined properties. In rare cases, however, the Universe offers a helping hand: To date a few SNe Ia have been observed that have had their luminosities magnified by intervening galaxies and galaxy clusters acting as gravitational lenses. In this paper, we present long-slit spectroscopy of the lensed SN Ia 2016geu, which occurred at a redshift of z = 0.409, and was magnified by a factor of ≈55 by a galaxy located at z = 0.216. We compared our spectra, which were obtained a couple of weeks to a couple of months past peak light, with the spectroscopic properties of well-observed, nearby SNe Ia, finding that SN 2016geu's properties are commensurate with those of SNe Ia in the local Universe. Based primarily on the velocity and strength of the Si II λ6355 absorption feature, we find that SN 2016geu can be classified as a high-velocity, high-velocity-gradient and 'corenormal' SN Ia. The strength of various features (measured though their pseudo-equivalent widths) argue against SN 2016geu being a faint, broad-lined, cool or shallow-silicon SN Ia. We conclude that the spectroscopic properties of SN 2016geu imply that it is a normal SN Ia, and when taking previous results by other authors into consideration, there is very little, if any, evolution in the observational properties of SNe Ia up to z ≈ 0.4.© 2018 The Authors., ZC acknowledges support from the Juan de la Cierva Incorporacion fellowship IJCI-2014-21669. AdUP acknowledges support from funding associated with the Ramon y Cajal fellowship RyC-2012-09975. DAK acknowledges support from the Juan de la Cierva Incorporacion fellowship IJCI-2015-26153. ZC, DAK and AdUP acknowledge support from the Spanish research project AYA 2014-58381-P. CG was funded by the Carlsberg Foundation.

We present observations of the dark Gamma-Ray Burst GRB 051008 provided by Swift/BAT, Swift/XRT, Konus-WIND, INTEGRAL/SPI-ACS in the high-energy domain and the Shajn, Swift/UVOT, Tautenburg, NOT, Gemini and Keck I telescopes in the optical and near-infrared bands. The burst was detected only in gamma- and X-rays and neither a prompt optical nor a radio afterglow were detected down to deep limits. We identified the host galaxy of the burst, which is a typical Lyman-break Galaxy (LBG) with R-magnitude of 24.06 +/- 0.10. A redshift of the galaxy of z = 2.77 (-0.20,+0.15) is measured photometrically due to the presence of a clear, strong Lyman-break feature. The host galaxy is a small starburst galaxy with moderate intrinsic extinction (A_V = 0.3 mag) and has a SFR of ~ 60 M_Sun / yr typical for LBGs. It is one of the few cases where a GRB host has been found to be a classical Lyman-break galaxy. Using the redshift we estimate the isotropic-equivalent radiated energy of the burst to be E_iso = (1.15 +/- 0.20) x 10^54 erg. We also provide evidence in favour of the hypothesis that the darkness of GRB 051008 is due to local absorption resulting from a dense circumburst medium., 15 pages, 8 figures Accepted to MNRAS

Context. GRB 111209A, one of the longest gamma-ray bursts (GRBs) ever observed, is linked to SN 2011kl, which is the most luminous GRB supernova (SN) detected so far. Several lines of evidence indicate that this GRB-SN is powered by a magnetar central engine. Aims. We place SN 2011kl into the context of large samples of SNe, addressing in more detail the question of whether this GRB-SN could be radioactively powered, and whether it represents an extreme version of a GRB-SN or an underluminous superluminous SN (SLSN). Methods. We modelled SN 2011kl using SN 1998bw as a template and derived a bolometric light curve including near-infrared data. We compared the properties of SN 2011kl to literature results on stripped-envelope and SLSNe. Results. A comparison in the k,- s context, i.e. comparing SN 2011kl to SN 1998bw templates in terms of luminosity and light-curve stretch, clearly shows SN 2011kl is the most luminous GRB-SN to date and is spectrally very dissimilar to other events because it is significantly bluer/hotter. Although SN 2011kl does not reach the classical luminosity threshold of SLSNe and evolves faster than any of these objects, it resembles SLSNe more than the classical GRB-associated broad-lined Type Ic SNe in several aspects. Conclusions. GRB 111209A was a very energetic event, both at early (prompt emission) and at very late (SN) times. We show in a companion publication that with the exception of the extreme duration, the GRB and afterglow parameters are in agreement with the known distributions for these parameters. SN 2011kl, on the other hand, is exceptional both in luminosity and spectral characteristics, indicating that GRB 111209A was likely not powered by a standard-model collapsar central engine, further supporting our earlier conclusions. Instead, it reveals the possibility of a direct link between GRBs and SLSNe.© ESO 2019., DAK acknowledges financial support by the DFG Cluster of Excellence >Origin and Structure of the Universe,> from MPE, from TLS, from the Spanish research project AYA 2014-58381-P, and from Juan de la Cierva Incorporacion fellowship IJCI-2015-26153. We are indebted to Joe Lyman and Vicki Toy for supplying the bolometric light curves of GRB 120422A/SN 2012bz and GRB 130702A/SN 2013dx, respectively. SK, DAK, ARossi, and ANG acknowledge support by DFG grants Kl 766/161 and Kl 766/16-3, SSchmidl also acknowledges the latter. ARossi acknowledges support from the Jenaer Graduiertenakademie and by the project PRININAF 2012 > The role of dust in galaxy evolution>. TK acknowledges support by the DFG Cluster of Excellence Origin and Structure of the Universe, and by the European Commission under the Marie Curie Intra-European Fellowship Programme. RF acknowledges support from European Regional Development Fund-Project > Engineering applications of microworld physics> (No. CZ.02.1.01/0.0/0.0/16_019/0000766). DARK is funded by the DNRF. FOE acknowledges funding of his Ph.D. through the DAAD, and support from FONDECYT through postdoctoral grant 3140326. SSchulze acknowledges support from CONICYT-Chile FONDECYT 3140534, Basal-CATA PFB-06/2007, and Project IC120009 >Millennium Institute of Astrophysics (MAS)> of Iniciativa Cientifica Milenio del Ministerio de Economia, Fomento y Turismo. SK, SSchmidl, and ANG acknowledge support by the Thuringer Ministerium fur Bildung, Wissenschaft und Kultur under FKZ 12010-514. MN and PS acknowledge support by DFG grant SA 2001/2-1. ANG, DAK, ARossi and AU are grateful for travel funding support through MPE.

We present the extensive follow-up campaign on the afterglow of GRB 110715A at 17 different wavelengths, from X-ray to radio bands, starting 81 seconds after the burst and extending up to 74 days later. We performed for the first time a GRB afterglow observation with the ALMA observatory. We find that the afterglow of GRB 110715A is very bright at optical and radio wavelengths. We use optical and near infrared spectroscopy to provide further information about the progenitor's environment and its host galaxy. The spectrum shows weak absorption features at a redshift z = 0.8225, which reveal a host galaxy environment with low ionization, column density and dynamical activity. Late deep imaging shows a very faint galaxy, consistent with the spectroscopic results. The broadband afterglow emission is modelled with synchrotron radiation using a numerical algorithm and we determine the best fit parameters using Bayesian inference in order to constrain the physical parameters of the jet and the medium in which the relativistic shock propagates. We fitted our data with a variety of models, including different density profiles and energy injections. Although the general behaviour can be roughly described by these models, none of them are able to fully explain all data points simultaneously. GRB 110715A shows the complexity of reproducing extensive multi-wavelength broadband afterglow observations, and the need of good sampling in wavelength and time and more complex models to accurately constrain the physics of GRB afterglows., Accepted for publication in MNRAS

Gamma-ray Burst 130427A had the largest fluence for almost 30 years. With an isotropic energy output of $8.5\times10^{53}$ erg and redshift of 0.34, it combined a very high energy release with a relative proximity to Earth in an unprecedented fashion. Sensitive X-ray facilities such as {\it XMM-Newton} and {\it Chandra} detected the afterglow of this event for a record-breaking baseline of 90 Ms. We show the X-ray light curve of GRB 130427A of this event over such an interval. The light curve shows an unbroken power law decay with a slope of $\alpha=1.31$ over more than three decades in time. In this presentation, we investigate the consequences of this result for the scenarios proposed to interpret GRB 130427A and the implications in the context of the forward shock model (jet opening angle, energetics, surrounding medium). We also remark the chance of extending GRB afterglow observations for several hundreds of Ms with {\it Athena}.

Tanvir, N.R. et. al., We report the discovery and monitoring of the near-infrared counterpart (AT2017gfo) of a binary neutron-star merger event detected as a gravitational wave source by Advanced Laser Interferometer Gravitational-wave Observatory (LIGO)/Virgo (GW170817) and as a short gamma-ray burst by Fermi Gamma-ray Burst Monitor (GBM) and Integral SPI-ACS (GRB 170817A). The evolution of the transient light is consistent with predictions for the behavior of a >kilonova/macronova> powered by the radioactive decay of massive neutron-rich nuclides created via r-process nucleosynthesis in the neutron-star ejecta. In particular, evidence for this scenario is found from broad features seen in Hubble Space Telescope infrared spectroscopy, similar to those predicted for lanthanide-dominated ejecta, and the much slower evolution in the near-infrared k-band compared to the optical. This indicates that the late-time light is dominated by high-opacity lanthanide-rich ejecta, suggesting nucleosynthesis to the third r-process peak (atomic masses A ≈ 195). This discovery confirms that neutron-star mergers produce kilo-/macronovae and that they are at least a major - if not the dominant - site of rapid neutron capture nucleosynthesis in the universe., A.J.L., D.S., and J.D.L. acknowledge support from STFC via grant ST/P000495/1. N.R.T. and A.J.L. have received funding from the European Research Council (ERC) under the European Union's Horizon 2020 Research and Innovation Programme (grant agreement No. 725246, TEDE, Levan). Ad.U.P., C.T., Z.C., and D.A.K. acknowledge support from the Spanish project AYA 2014-58381-P. Z.C. also acknowledges support from the Juan de la Cierva Incorporacion fellowship IJCI-2014-21669, and D.A.K. from Juan de la Cierva Incorporacion fellowship IJCI-2015-26153. J.H. is supported by a VILLUM FONDEN Investigator grant (project number 16599). P.D.A., S.C., and A.M. acknowledge support from the ASI grant I/004/11/3. S.R. has been supported by the Swedish Research Council (VR) under grant No. 2016-03657_3, by the Swedish National Space Board under grant No. Dnr. 107/16, and by the research environment grant >Gravitational Radiation and Electromagnetic Astrophysical Transients (GREAT)> funded by the Swedish Research council (VR) under Dnr 2016-06012.

We present multi-wavelength observations of the dark GRB 051008. The burst was not detected in the optical bands, however we discover the host galaxy and secured the redshift of the host with following campaign of multicolor observations of Shajn, NOT, Gemini North and Keck telescopes. We provide arguments that the galaxy could be in a complex of gravitationally bound galaxies. Our investigation of the GRB 051008 also confirms a tendency of host galaxies of dark bursts to be more dusty.

Aims. The aim of the study is to constrain the physics of gamma-ray bursts (GRBs) by analysing the multi-wavelength afterglow data set of GRB 121024A that covers the full range from radio to X-rays. Methods. Using multi-epoch broad-band observations of the GRB 121024A afterglow, we measured the three characteristic break frequencies of the synchrotron spectrum. We used six epochs of combined XRT and GROND data to constrain the temporal slopes, the dust extinction, the X-ray absorption, and the spectral slope with high accuracy. Two more epochs of combined data from XRT, GROND, APEX, CARMA, and EVLA were used to set constraints on the break frequencies and therefore on the micro-physical and dynamical parameters. Results. The XRT and GROND light curves show a simultaneous and achromatic break at around 49 ks. As a result, the crossing of the synchrotron cooling break is no suitable explanation for the break in the light curve. The multi wavelength data allow us to test two plausible scenarios explaining the break: a jet break, and the end of energy injection. The jet-break scenario requires a hard electron spectrum, a very low cooling break frequency, and a non-spreading jet. The energy injection avoids these problems, but requires $\epsilon_e > 1 (k = 2)$, spherical outflow, and $\epsilon_B < 10^{-9}$. Conclusions. In light of the extreme microphysical parameters required by the energy-injection model, we favour a jet-break scenario where $\nu_m < \nu_{sa}$ to explain the observations. This scenario gives physically meaningful microphysical parameters, and it also naturally explains the reported detection of linear and circular polarisation., Comment: Final accepted version