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SOXS (Son Of X-Shooter) is a single object spectrograph built by an international consortium for the ESO NTT telescope. SOXS is based on the heritage of the X-Shooter at the ESO-VLT with two arms (UV-VIS and NIR) working in parallel, with a Resolution-Slit product of about 4500, capable of simultaneously observing over the entire band the complete spectral range from the U- to the H-band. SOXS will carry out rapid and long-term Target of Opportunity requests on a variety of astronomical objects. The SOXS vacuum and cryogenic control system has been designed to evacuate, cool down and maintain the UV-VIS detector and the entire NIR spectrograph to their operating temperatures. The design chosen allows the two arms to be operated independently. This paper describes the final design of the cryo-vacuum control system, its functionalities and the tests performed in the integration laboratories., 12 pages, 6 figures, SPIE proceedings of the conference Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation IV

We report the implemented architecture for monitoring the health and the quality of the Son Of X-Shooter (SOXS) spectrograph for the New Technology Telescope in La Silla at the European Southern Observatory. Briefly, we report on the innovative no-SQL database approach used for storing time-series data that best suits for automatically triggering alarm, and report high-quality graphs on the dashboard to be used by the operation support team. The system is designed to constantly and actively monitor the Key Performance Indicators (KPI) metrics, as much automatically as possible, reducing the overhead on the support and operation teams. Moreover, we will also detail about the interface designed to inject quality checks metrics from the automated SOXS Pipeline (Young et al. 2022).

SOXS (Son Of X-Shooter) is a single object spectrograph offering a simultaneous spectral coverage from U- to H-band, built by an international consortium for the 3.58-m ESO New Technology Telescope at the La Silla Observatory. It is designed to observe all kind of transients and variable sources discovered by different surveys with a highly flexible schedule maintained by the consortium, based on the Target of Opportunity concept. SOXS is going to be a fundamental spectroscopic partner for any kind of imaging survey, becoming one of the premier transient follow-up instruments in the Southern hemisphere. This paper gives an updated status of the project, when the instrument is in the advanced phase of integration and testing in Europe, prior to the activities in Chile., Proc. SPIE 12184, Ground-based and Airborne Instrumentation for Astronomy IX, 121840O (2022)

The Son Of X-Shooter (SOXS) is a single object spectrograph, built by an international consortium for the 3.58-m ESO New Technology Telescope at the La Silla Observatory, ranging from 350 to 2000 nm. In this paper, we present the progress in the AIT phase of the Near InfraRed (NIR) arm. We describe the different AIT phases of the cryo, vacuum, opto-mechanics and detector subsystems, that finally converged at the INAF-OAB premises in Merate (Italy), where the NIR spectrograph is currently being assembled and tested, before the final assembly on SOXS., Comment: 6 pages, 8 Figures, SPIE: Astronomical Telescope + Instrumentation, Montreal 2022

SOXS is the new spectrograph for the ESO NTT telescope able to cover the optical and NIR bands thanks to two different arms: the UV-VIS (350-850 nm), and the NIR (800-2000 nm). In this article, we describe the final design of the visible camera cryostats, the test facilities for the CCD characterization, and the first results with the scientific detector. The UV-VIS detector system is based on a e2v CCD 44-82, a custom detector head coupled with the ESO Continuous Flowing Cryostat (CFC) cooling system and the New General Detector Controller (NGC) developed by ESO. The laboratory facility is based on an optical bench equipped with a Xenon lamp, filter wheels to select the wavelength, an integrating sphere, and a calibrated diode to measure the flux. This paper outlines the visible camera cryostat, the test facilities for the CCD characterization and the first results with the scientific detector in the laboratory and after the integration to the instrument.

The tidal forces of a black hole can rip apart a star that passes too close to it, resulting in a stellar Tidal Disruption Event (TDE, (1)). In some such encounters, the black hole can launch a powerful relativistic jet (2-6). If this jet fortuitously aligns with our line of sight, the overall brightness is Doppler boosted by several orders of magnitude. Consequently, such on-axis relativistic TDEs have the potential to unveil cosmological (redshift z>1) quiescent black holes and are ideal test beds to understand the radiative mechanisms operating in super-Eddington jets. Here, we present multi-wavelength (X-ray, UV, optical, and radio) observations of the optically discovered transient AT 2022cmc at z=1.193 (7). Its unusual X-ray properties, including a peak observed luminosity of >1048 erg s-1, systematic variability on timescales as short as 1000 seconds, and overall duration lasting more than 30 days in the rest-frame are traits associated with relativistic TDEs. This makes AT 2022cmc only the fourth member of this rare class and the first one identified in the optical and with well-sampled optical data. The X-ray to radio spectral energy distributions spanning 5-50 days after discovery can be explained as synchrotron emission from a relativistic jet (radio), synchrotron self-Compton (X-rays), and thermal emission similar to that seen in low-redshift TDEs (UV/optical). Our modeling implies a beamed, highly relativistic jet akin to blazars (e.g., (8,9)) but requires extreme matter-domination, i.e, high ratio of electron-to-magnetic field energy densities in the jet, and challenges our theoretical understanding of jets. This work provides one of the best multi-wavelength datasets of a newborn relativistic jet to date and will be invaluable for testing more sophisticated jet models, and for identifying more such events in transient surveys.

Large-scale sky surveys have played a transformative role in our understanding of astrophysical transients, only made possible by increasingly powerful machine learning-based filtering to accurately sift through the vast quantities of incoming data generated. In this paper, we present a new real-bogus classifier based on a Bayesian convolutional neural network that provides nuanced, uncertainty-aware classification of transient candidates in difference imaging, and demonstrate its application to the datastream from the GOTO wide-field optical survey. Not only are candidates assigned a well-calibrated probability of being real, but also an associated confidence that can be used to prioritise human vetting efforts and inform future model optimisation via active learning. To fully realise the potential of this architecture, we present a fully-automated training set generation method which requires no human labelling, incorporating a novel data-driven augmentation method to significantly improve the recovery of faint and nuclear transient sources. We achieve competitive classification accuracy (FPR and FNR both below 1%) compared against classifiers trained with fully human-labelled datasets, whilst being significantly quicker and less labour-intensive to build. This data-driven approach is uniquely scalable to the upcoming challenges and data needs of next-generation transient surveys. We make our data generation and model training codes available to the community., 17 pages, 12 figures, resubmitted to MNRAS following reviewer comments

We present the results of a multi-wavelength follow up campaign for the luminous nuclear transient Gaia16aax, which was first identified in January 2016. The transient is spatially consistent with the nucleus of an active galaxy at z=0.25, hosting a black hole of mass $\rm \sim6\times10^8M_\odot$. The nucleus brightened by more than 1 magnitude in the Gaia G-band over a timescale of less than one year, before fading back to its pre-outburst state over the following three years. The optical spectra of the source show broad Balmer lines similar to the ones present in a pre-outburst spectrum. During the outburst, the $\rm H\alpha$ and $\rm H\beta$ emission lines develop a secondary peak. We also report on the discovery of two transients with similar light curve evolution and spectra: Gaia16aka and Gaia16ajq. We consider possible scenarios to explain the observed outbursts. We exclude that the transient event could be caused by a microlensing event, variable dust absorption or a tidal encounter between a neutron star and a stellar mass black hole in the accretion disk. We consider variability in the accretion flow in the inner part of the disk, or a tidal disruption event of a star $\geq 1 M_{\odot}$ by a rapidly spinning supermassive black hole as the most plausible scenarios. We note that the similarity between the light curves of the three Gaia transients may be a function of the Gaia alerts selection criteria., Comment: 21 pages, 17 figure - accepted for publication in MNRAS main journal

The Son Of X-Shooter (SOXS) is a two-channel spectrograph along with imaging capabilities, characterized by a wide spectral coverage (350nm to 2000nm), designed for the NTT telescope at the La Silla Observatory. Its main scientific goal is the spectroscopic follow-up of transients and variable objects. The UV-VIS arm, of the Common Path sub-system, is characterized by the presence of a powered Atmospheric Dispersion Corrector composed (ADC) by two counter-rotating quadruplets, two prisms, and two lenses each. The presence of powered optics in both the optical groups represents an additional challenge in the alignment procedures. We present the characteristics of the ADC, the analysis after receiving the optics from the manufacturer, the emerging issues, the alignment strategies we followed, and the final results of the ADC in dispersion and optical quality.

SOXS (SOn of X-Shooter) is a medium resolution (~4500) wide-band (0.35 - 2.0 {\mu}m) spectrograph which passed the Final Design Review in 2018. The instrument is in the final integration phase and it is planned to be installed at the NTT in La Silla by next year. It is mainly composed of five different optomechanical subsystems (Common Path, NIR spectrograph, UV-VIS spectrograph, Camera, and Calibration) and other mechanical subsystems (Interface flange, Platform, cable corotator, and cooling system). A brief overview of the optomechanical subsystems is presented here as more details can be found in the specific proceedings while a more comprehensive discussion is dedicated to the other mechanical subsystems and the tools needed for the integration of the instrument. Moreover, the results obtained during the acceptance of the various mechanical elements are presented together with the experiments performed to validate the functionality of the subsystems. Finally, the mechanical integration procedure is shown here, along with all the modifications applied to correct the typical problems happening in this phase., Comment: arXiv admin note: text overlap with arXiv:2012.12693

Type Ia supernovae (SNe Ia) are thermonuclear explosions of degenerate white dwarf (WD) stars destabilized by mass accretion from a companion star, but the nature of their progenitors remains poorly understood. A way to discriminate between progenitor systems is through radio observations; a non-degenerate companion star is expected to lose material through winds or binary interaction prior to explosion, and the SN ejecta crashing into this nearby circumstellar material (CSM) should result in radio synchrotron emission. However, despite extensive efforts, no SN Ia has ever been detected at radio wavelengths, which suggests a clean environment and a companion star that is itself a degenerate WD star. Here we report on the study of SN 2020eyj, a SN Ia showing helium-rich CSM, as revealed by its spectral features, infrared emission and, for the first time in a SN Ia, a radio counterpart. Based on our modeling, we conclude the CSM likely originates from a single-degenerate (SD) binary system where a WD accretes material from a helium donor star, an often hypothesized formation channel for SNe Ia. We describe how comprehensive radio follow-up of SN 2020eyj-like SNe Ia can improve the constraints on their progenitor systems., Comment: 62 pages, 10 figures, 4 tables

We present development progress of the scheduler for the Son Of X-Shooter (SOXS) instrument at the ESO-NTT 3.58 meter telescope. SOXS will be a single object spectroscopic facility, consisting of a two-arms high-efficiency spectrograph covering the spectral range 350-2000 nanometer with a mean resolving power R$\approx$4500. SOXS will be uniquely dedicated to the UV-visible and near infrared follow up of astrophysical transients, with a very wide pool of targets available from the streaming services of wide-field telescopes, current and future. This instrument will serve a variety of scientific scopes in the astrophysical community, with each scope eliciting its specific requirements for observation planning, that the observing scheduler has to meet. Due to directions from the European Southern Observatory (ESO), the instrument will be operated only by La Silla staff, with no astronomer present on the mountain. This implies a new challenge for the scheduling process, requiring a fully automated algorithm that should be able to present the operator not only with and ordered list of optimal targets, but also with optimal back-ups, should anything in the observing conditions change. This imposes a fast-response capability to the scheduler, without compromising the optimization process, that ensures good quality of the observations. In this paper we present the current state of the scheduler, that is now almost complete, and of its web interface., Accepted for publication in SPIE Astronomical Telescope and Instrumentation Conference proceedings - Montreal (Canada) July 2022

SOXS (SOn of X-Shooter) is a high-efficiency spectrograph with a mean Resolution-Slit product of 3500 over the entire band capable of simultaneously observing the complete spectral range 350-2000 nm. It consists of three scientific arms (the UV-VIS Spectrograph, the NIR Spectrograph and the Acquisition Camera) connected by the Common Path system to the NTT, and the Calibration Unit. We present an overview of the flow from the scientific to the technical requirements, and the realization of the sub-systems. Further, we give an overview of the methodologies used for planning and managing the assembly of the sub-systems, their integration and tests before the acceptance of the instrument in Europe (PAE) along with the plan for the integration of SOXS to the NTT. SOXS could be used as an example for the system engineering of an instrument of moderate complexity, with a large geographic spread of the team., Comment: 12 pages, 4 Figures, SPIE: Astronomical Telescope + Instrumentation, Montreal 2022. arXiv admin note: text overlap with arXiv:1812.07401

The Son-Of-XShooter (SOXS) is a single object spectrograph (UV-VIS & NIR) and acquisition camera scheduled to be mounted on the ESO 3.58-m New Technology Telescope at the La Silla Observatory. Although the underlying data reduction processes to convert raw detector data to fully-reduced science ready data are complex and multi-stepped, we have designed the SOXS Data Reduction pipeline with the core aims of providing end-users with a simple-to-use, well-documented command-line interface while also allowing the pipeline to be run in a fully automated state; streaming reduced data into the ESO Science Archive Facility without need for human intervention. To keep up with the stream of data coming from the instrument, there is the requirement to optimise the software to reduce each observation block of data well within the typical observation exposure time. The pipeline is written in Python 3 and has been built with an agile development philosophy that includes CI and adaptive planning., 10 pages, 7 figures, published in SPIE proceedings volume 12189. arXiv admin note: substantial text overlap with arXiv:2012.12678

The typical detection rate of $\sim1$ gamma-ray burst (GRB) per day by the \emph{Fermi} Gamma-ray Burst Monitor (GBM) provides a valuable opportunity to further our understanding of GRB physics. However, the large uncertainty of the \emph{Fermi} localization typically prevents rapid identification of multi-wavelength counterparts. We report the follow-up of 93 \emph{Fermi} GRBs with the Gravitational-wave Optical Transient Observer (GOTO) prototype on La Palma. We selected 53 events (based on favourable observing conditions) for detailed analysis, and to demonstrate our strategy of searching for optical counterparts. We apply a filtering process consisting of both automated and manual steps to 60\,085 candidates initially, rejecting all but 29, arising from 15 events. With $\approx3$ GRB afterglows expected to be detectable with GOTO from our sample, most of the candidates are unlikely to be related to the GRBs. Since we did not have multiple observations for those candidates, we cannot confidently confirm the association between the transients and the GRBs. Our results show that GOTO can effectively search for GRB optical counterparts thanks to its large field of view of $\approx40$ square degrees and its depth of $\approx20$ mag. We also detail several methods to improve our overall performance for future follow-up programs of \emph{Fermi} GRBs.

Cay, Y. Z., et al., We present the spectroscopic and photometric study of five intermediate-luminosity red transients (ILRTs), namely AT 2010dn, AT 2012jc, AT 2013la, AT 2013lb, and AT 2018aes. They share common observational properties and belong to a family of objects similar to the prototypical ILRT SN 2008S. These events have a rise time that is less than 15 days and absolute peak magnitudes of between-11.5 and-14.5 mag. Their pseudo-bolometric light curves peak in the range 0.5-9.0 × 1040 erg s-1 and their total radiated energies are on the order of (0.3-3) × 1047 erg. After maximum brightness, the light curves show a monotonic decline or a plateau, resembling those of faint supernovae IIL or IIP, respectively. At late phases, the light curves flatten, roughly following the slope of the 56Co decay. If the late-time power source is indeed radioactive decay, these transients produce 56Ni masses on the order of 10-4 to 10-3 M⊙. The spectral energy distribution of our ILRT sample, extending from the optical to the mid-infrared (MIR) domain, reveals a clear IR excess soon after explosion and non-negligible MIR emission at very late phases. The spectra show prominent H lines in emission with a typical velocity of a few hundred km s-1, along with Ca II features. In particular, the [Ca II] λ7291,7324 doublet is visible at all times, which is a characteristic feature for this family of transients. The identified progenitor of SN 2008S, which is luminous in archival Spitzer MIR images, suggests an intermediate-mass precursor star embedded in a dusty cocoon. We propose the explosion of a super-asymptotic giant branch star forming an electron-capture supernova as a plausible explanation for these events.

The advent of wide-field sky surveys has led to the growth of transient and variable source discoveries. The data deluge produced by these surveys has necessitated the use of machine learning (ML) and deep learning (DL) algorithms to sift through the vast incoming data stream. A problem that arises in real-world applications of learning algorithms for classification is imbalanced data, where a class of objects within the data is underrepresented, leading to a bias for over-represented classes in the ML and DL classifiers. We present a recurrent neural network (RNN) classifier that takes in photometric time-series data and additional contextual information (such as distance to nearby galaxies and on-sky position) to produce real-time classification of objects observed by the Gravitational-wave Optical Transient Observer (GOTO), and use an algorithm-level approach for handling imbalance with a focal loss function. The classifier is able to achieve an Area Under the Curve (AUC) score of 0.972 when using all available photometric observations to classify variable stars, supernovae, and active galactic nuclei. The RNN architecture allows us to classify incomplete light curves, and measure how performance improves as more observations are included. We also investigate the role that contextual information plays in producing reliable object classification., Comment: 16 pages, 12 figures, to be published in Monthly Notices of the Royal Astronomical Society

ASASSN-18am/SN 2018gk is a newly discovered member of the rare group of luminous, hydrogen-rich supernovae (SNe) with a peak absolute magnitude of MV ≈ −20 mag that is in between normal core-collapse SNe and superluminous SNe. These SNe show no prominent spectroscopic signatures of ejecta interacting with circumstellar material (CSM), and their powering mechanism is debated. ASASSN-18am declines extremely rapidly for a Type II SN, with a photospheric-phase decline rate of ∼6.0 mag (100 d)−1. Owing to the weakening of H i and the appearance of He i in its later phases, ASASSN-18am is spectroscopically a Type IIb SN with a partially stripped envelope. However, its photometric and spectroscopic evolution shows significant differences from typical SNe IIb. Using a radiative diffusion model, we find that the light curve requires a high synthesized 56Ni mass $M_{\rm Ni} \sim 0.4\, \rm {M_{\odot }}$ and ejecta with high kinetic energy Ekin = (7–10) × 1051 erg. Introducing a magnetar central engine still requires $M_{\rm Ni} \sim 0.3\, \rm {M_{\odot }}$ and Ekin = 3 × 1051 erg. The high 56Ni mass is consistent with strong iron-group nebular lines in its spectra, which are also similar to several SNe Ic-BL with high 56Ni yields. The earliest spectrum shows ‘flash ionization’ features, from which we estimate a mass-loss rate of $\dot{M}\approx 2\times 10^{-4} \, \rm \rm {M_{\odot }}\,yr^{-1}$. This wind density is too low to power the luminous light curve by ejecta–CSM interaction. We measure expansion velocities as high as 17 000 $\rm {\, km\, s^{-1}}$ for Hα, which is remarkably high compared to other SNe II. We estimate an oxygen core mass of 1.8–3.4 M⊙ using the [O i] luminosity measured from a nebular-phase spectrum, implying a progenitor with a zero-age main-sequence mass of 19–26 M⊙.

Acknowledgements. We thank the anonymous referee for useful comments. We thank Marco Fiaschi for carrying out some of the Asiago observations. EK is supported by the Turku Collegium of Science, Medicine and Technology. EK also acknowledge support from the Science and Technology Facilities Council (STFC; ST/P000312/1). ECK acknowledges support from the G.R.E.A.T. research environment and support from The Wenner-Gren Foundations. MF is supported by a Royal Society – Science Foundation Ireland University Research Fellowship. EC, LT, AP, and MT are partially supported by the PRIN-INAF 2017 with the project “Towards the SKA and CTA era: discovery, localization, and physics of transient objects”. HK was funded by the Academy of Finland projects 324504 and 328898. TWC acknowledges the EU Funding under Marie Skłodowska-Curie grant agreement No. 842471. LG was funded by the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 839090. This work has been partially supported by the Spanish grant PGC2018-095317-B-C21 within the European Funds for Regional Development (FEDER). MG is supported by the Polish NCN MAESTRO grant 2014/14/A/ST9/00121. KM acknowledges support from EU H2020 ERC grant no. 758638. TMB was funded by the CONICYT PFCHA / DOCTORADOBECAS CHILE/2017-72180113. MN is supported by a Royal Astronomical Society Research Fellowship. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programmes 67.D-0438, 60.A-9475, 199.D-0143, and 1103.D-0328. Some of the observations reported in this paper were obtained with the Southern African Large Telescope (SALT) under programme 2018-1-DDT-003 (PI: Kankare). Polish participation in SALT is funded by grant No. MNiSW DIR/WK/2016/07. Based on observations made with the Nordic Optical Telescope, operated by the Nordic Optical Telescope Scientific Association at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofisica de Canarias. The data presented here were obtained in part with ALFOSC, which is provided by the Instituto de Astrofisica de Andalucia (IAA) under a joint agreement with the University of Copenhagen and NOTSA. This work is partly based on the NUTS2 programme carried out at the NOT. NUTS2 is funded in part by the Instrument Center for Danish Astrophysics (IDA). The Liverpool Telescope is operated on the island of La Palma by Liverpool John Moores University in 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. This paper is also based on observations collected at the Copernico 1.82 m and Schmidt 67/92 Telescopes operated by INAF – Osservatorio Astronomico di Padova at Asiago, Italy. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina), and Ministério da Ciência, Tecnologia e Inovação (Brazil). Observations were carried out under programme GS-2017A-C-1. This project used data obtained with the Dark Energy Camera (DECam), which was constructed by the Dark Energy Survey (DES) collaboration. Funding for the DES Projects has been provided by the DOE and NSF (USA), MISE (Spain), STFC (UK), HEFCE (UK), NCSA (UIUC), KICP (U. Chicago), CCAPP (Ohio State), MIFPA (Texas A&M University), CNPQ, FAPERJ, FINEP (Brazil), MINECO (Spain), DFG (Germany) and the collaborating institutions in the Dark Energy Survey, which are Argonne Lab, UC Santa Cruz, University of Cambridge, CIEMAT-Madrid, University of Chicago, University College London, DES-Brazil Consortium, University of Edinburgh, ETH Zürich, Fermilab, University of Illinois, ICE (IEEC-CSIC), IFAE Barcelona, Lawrence Berkeley Lab, LMU München and the associated Excellence Cluster Universe, University of Michigan, NOAO, University of Nottingham, Ohio State University, OzDES Membership Consortium, University of Pennsylvania, University of Portsmouth, SLAC National Lab, Stanford University, University of Sussex, and Texas A&M University. Based on observations obtained with the Samuel Oschin 48-inch Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. ZTF is supported by the National Science Foundation under Grant No. AST-1440341 and a collaboration including Caltech, IPAC, the Weizmann Institute for Science, the Oskar Klein Center at Stockholm University, the University of Maryland, the University of Washington, Deutsches Elektronen-Synchrotron and Humboldt University, Los Alamos National Laboratories, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee, and Lawrence Berkeley National Laboratories. Operations are conducted by COO, IPAC, and UW. Based on observations at Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory (NOAO Prop. ID 2017A-0260; and PI: Soares-Santos), which is operated by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation. The Pan-STARRS1 Surveys (PS1) and the PS1 public science archive have been made possible through contributions by 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, the Queen’s University Belfast, the Harvard-Smithsonian Center for Astrophysics, the Las Cumbres Observatory Global Telescope Network Incorporated, the National Central University of Taiwan, the Space Telescope Science Institute, the National Aeronautics and Space Administration under Grant No. NNX08AR22G issued through the Planetary Science Division of the NASA Science Mission Directorate, the National Science Foundation Grant No. AST-1238877, the University of Maryland, Eotvos Lorand University (ELTE), the Los Alamos National Laboratory, and the Gordon and Betty Moore Foundation. Some of the data presented in this paper were obtained from the Mikulski Archive for Space Telescopes (MAST). STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. This work is based in part on archival data obtained with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. This research has made use of NED which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. We have made use of the Weizmann Interactive Supernova Data Repository (Yaron & Gal-Yam 2012, https://wiserep.weizmann.ac.il)., 1 iraf is distributed by the National Optical Astronomy Observatories, which are operated by the Association of Universities for Research in Astronomy, Inc., under cooperative agreement with the National Science Foundation., The fraction of core-collapse supernovae (CCSNe) occurring in the central regions of galaxies is not well constrained at present. This is partly because large-scale transient surveys operate at optical wavelengths, making it challenging to detect transient sources that occur in regions susceptible to high extinction factors. Here we present the discovery and follow-up observations of two CCSNe that occurred in the luminous infrared galaxy (LIRG) NGC 3256. The first, SN 2018ec, was discovered using the ESO HAWK-I/GRAAL adaptive optics seeing enhancer, and was classified as a Type Ic with a host galaxy extinction of AV = 2.1−0.1+0.3 mag. The second, AT 2018cux, was discovered during the course of follow-up observations of SN 2018ec, and is consistent with a subluminous Type IIP classification with an AV = 2.1 ± 0.4 mag of host extinction. A third CCSN, PSN J10275082−4354034 in NGC 3256, was previously reported in 2014, and we recovered the source in late-time archival Hubble Space Telescope imaging. Based on template light curve fitting, we favour a Type IIn classification for it with modest host galaxy extinction of AV = 0.3−0.3+0.4 mag. We also extend our study with follow-up data of the recent Type IIb SN 2019lqo and Type Ib SN 2020fkb that occurred in the LIRG system Arp 299 with host extinctions of AV = 2.1−0.3+0.1 and AV = 0.4−0.2+0.1 mag, respectively. Motivated by the above, we inspected, for the first time, a sample of 29 CCSNe located within a projected distance of 2.5 kpc from the host galaxy nuclei in a sample of 16 LIRGs. We find, if star formation within these galaxies is modelled assuming a global starburst episode and normal IMF, that there is evidence of a correlation between the starburst age and the CCSN subtype. We infer that the two subgroups of 14 H-poor (Type IIb/Ib/Ic/Ibn) and 15 H-rich (Type II/IIn) CCSNe have different underlying progenitor age distributions, with the H-poor progenitors being younger at 3σ significance. However, we note that the currently available sample sizes of CCSNe and host LIRGs are small, and the statistical comparisons between subgroups do not take into account possible systematic or model errors related to the estimated starburst ages., DOCTORADOBECAS CHILE/2017-72180113, Deutsches Elektronen-Synchrotron and Humboldt University, EU H2020 ERC 758638, IFAE Barcelona, IPAC, Instituto de Astrofisica de Canarias, KICP, MIFPA, Marie Skłodowska-Curie 839090,PGC2018-095317-B-C21, Max Planck Institute for Astronomy, Max Planck Institute for Extraterrestrial Physics, NOAO, National Central University of Taiwan, National Optical Astronomy Observatories, Science Foundation Ireland University, Turku Collegium of Science, Medicine and Technology, Weizmann Institute for Science, National Science Foundation NSF, U.S. Department of Energy USDOE, National Aeronautics and Space Administration AST-1238877,NNX08AR22G NASA, Gordon and Betty Moore Foundation NAS5-26555 GBMF, Merck Institute for Science Education MISE, University of Illinois at Urbana-Champaign UIUC, Stanford University SU, Argonne National Laboratory ANL, Lawrence Berkeley National Laboratory 2017A-0260 LBNL, University of Wisconsin-Milwaukee, Ohio State University OSU, California Institute of Technology CIT, University of Chicago, University of Michigan U-M, University of Washington UW, Johns Hopkins University JHU, Texas A and M University TAMU, University of Maryland UMD, University of Hawai'i UH, Los Alamos National Laboratory LANL, University of Portsmouth, Smithsonian Astrophysical Observatory SAO, National Centre for Supercomputing Applications NCSA, Horizon 2020 Framework Programme H2020, SLAC National Accelerator Laboratory SLAC, National Research Council NRC, Space Telescope Science Institute STScI, Center for Cosmology and Astroparticle Physics, Ohio State University CCAPP, Wenner-Gren Stiftelserna, Science and Technology Facilities Council ST/P000312/1 STFC, Royal Society, Royal Astronomical Society MNiSW DIR/WK/2016/07 RAS, University College London UCL, European Commission 842471 EC, University of Nottingham, University of Sussex AST-1440341, University of Edinburgh ED, Queen's University Belfast QUB, Durham University, Deutsche Forschungsgemeinschaft DFG, Suomen Akatemia 324504,328898, Comisión Nacional de Investigación Científica y Tecnológica CONICYT, Ministerio de Ciencia, Tecnología e Innovación Productiva MINCyT, Ministerio de Economía y Competitividad MINECO, Ministério da Ciência, Tecnologia e Inovação MCTI, Liverpool John Moores University LJMU, Max-Planck-Gesellschaft MPG, Narodowe Centrum Nauki 2014/14/A/ST9/00121 NCN, Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro FAPERJ, Financiadora de Estudos e Projetos FINEP, European Regional Development Fund ERDF, Eötvös Loránd Tudományegyetem ELTE

Davis, S., et al., We present a study of the optical and near-infrared (NIR) spectra of SN 2013ai along with its light curves. These data range from discovery until 380 days after explosion. SN 2013ai is a fast declining Type II supernova (SN II) with an unusually long rise time, 18.9 2.7 days in the V-band, and a bright V-band peak absolute magnitude of -18.7 0.06 mag. The spectra are dominated by hydrogen features in the optical and NIR. The spectral features of SN 2013ai are unique in their expansion velocities, which, when compared to large samples of SNe II, are more than 1,000 km s-1 faster at 50 days past explosion. In addition, the long rise time of the light curve more closely resembles SNe IIb rather than SNe II. If SN 2013ai is coeval with a nearby compact cluster, we infer a progenitor zero-age main-sequence mass of ∼17 M o˙. After performing light-curve modeling, we find that SN 2013ai could be the result of the explosion of a star with little hydrogen mass, a large amount of synthesized 56Ni, 0.3-0.4 M o˙, and an explosion energy of 2.5-3.0 1051 erg. The density structure and expansion velocities of SN 2013ai are similar to those of the prototypical SN IIb, SN 1993J. However, SN 2013ai shows no strong helium features in the optical, likely due to the presence of a dense core that prevents the majority of γ-rays from escaping to excite helium. Our analysis suggests that SN 2013ai could be a link between SNe II and stripped-envelope SNe., The work of the CSP-II has been generously supported by the National Science Foundation under grants AST-1008343, AST1613426, AST-1613455, and AST1613472. The CSP-II was also supported in part by the Danish Agency for Science and Technology and Innovation through a Sapere Aude Level 2 grant. M.F. is supported by a Royal Society—Science Foundation Ireland University Research Fellowship. P.H. acknowledges support by grants of the NSF AST-1008962 and NASA’s ATP1909476. L.G. was funded by the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No. 839090. This work has been partially supported by the Spanish grant PGC2018-095317- B-C21 within the European Funds for Regional Development (FEDER). T.W.C. acknowledges the EU Funding under Marie Skłodowska-Curie grant agreement No 842471. M.S. is supported by generous grants from Villum FONDEN (13261, 28021) and by a project grant (8021-00170B) awarded by the Independent Research Fund Denmark.

We thank the anonymous referee for the comments and suggestions that have helped to improve the paper. We are grateful to Peter Jonker who enabled the WHT observation of this target during his program W19AN003. We thank Peter Brown its contribution with data from the Neil Gehrels Swift Observatory. CPG and MS acknowledge support from EU/FP7-ERC grant No. [615929]. MO acknowledges support from UNRN PI2018 40B696 grant. GP acknowledges support by ANID – Millennium Science Initiative – ICN12_009. NER acknowledges support from MIUR, PRIN 2017 (grant 20179ZF5KS). MF is supported by a Royal Society - Science Foundation Ireland University Research Fellowship. MS is supported by generous grants from VILLUM FONDEN (13261, 28021) and by a project grant (8021-00170B) from the Independent Research Fund Denmark. LG was funded by the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 839090. JB, DH, DAH, and CP were supported by NSF grant AST-1911225. TMB was funded by the CONICYT PFCHA / DOCTORADOBECAS CHILE/2017-72180113. This work has been partially supported by the Spanish grant PGC2018-095317-B-C21 within the European Funds for Regional Development (FEDER). Based on observations made with the Nordic Optical Telescope, owned in collaboration by theUniversity 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, the University of Iceland and Stockholm University at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofisica de Canarias. Observations from the NOT were obtained through the NUTS and NUTS2 collaboration which are supported in part by the Instrument Centre for Danish Astrophysics (IDA). The data presented here were obtained in part with ALFOSC, which is provided by the Instituto de Astrofisica de Andalucia (IAA) under a joint agreement with the University of Copenhagen and NOTSA. Based on observations made with the GTC telescope, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, under Director’s Discretionary Time. This work has made use of data from the Asteroid Terrestrialimpact Last Alert System (ATLAS) project. ATLAS is primarily funded to search for near earth asteroids through NASA grants NN12AR55G, 80NSSC18K0284, and 80NSSC18K1575; by products of the NEO search include images and catalogues from the survey area. The ATLAS science products have been made possible through the contributions of the University of Hawaii Institute for Astronomy, the Queen’s University Belfast, the Space Telescope Science Institute, and the South African Astronomical Observatory. The Liverpool Telescope is operated on the island of La Palma by Liverpool John Moores University in 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. This work makes use of data from the Las Cumbres Observatory network., We present the photometric and spectroscopic evolution of supernova (SN) 2019cad during the first similar to 100 d from explosion. Based on the light-curve morphology, we find that SN 2019cad resembles the double-peaked Type Ib/c SN 2005bf and the Type Ic PTF11mnb. Unlike those two objects, SN 2019cad also shows the initial peak in the redder bands. Inspection of the g-band light curve indicates the initial peak is reached in similar to 8 d, while the r-band peak occurred similar to 15 d post-explosion. A second and more prominent peak is reached in all bands at similar to 45 d past explosion, followed by a fast decline from similar to 60 d. During the first 30 d, the spectra of SN 2019cad show the typical features of a Type Ic SN, however, after 40 d, a blue continuum with prominent lines of Si II lambda 6355 and C II lambda 6580 is observed again. Comparing the bolometric light curve to hydrodynamical models, we find that SN 2019cad is consistent with a pre-SN mass of 11 M-circle dot, and an explosion energy of 3.5 x 10(51) erg. The light-curve morphology can be reproduced either by a double-peaked Ni-56 distribution with an external component of 0.041 M-circle dot, and an internal component of 0.3 M-circle dot or a double-peaked Ni-56 distribution plus magnetar model (P similar to 11 ms and B similar to 26 x 10(14) G). If SN 2019cad were to suffer from significant host reddening (which cannot be ruled out), the Ni-56 model would require extreme values, while the magnetar model would still be feasible., European Commission 615929, UNRN PI2018 40B696, Ministry of Education, Universities and Research (MIUR), Research Projects of National Relevance (PRIN) 20179ZF5KS, Science Foundation Ireland, Magnus Ehrnrooth foundation, Vilho, Yrjo and Kalle Vaisala Foundation of the Finnish academy of Science and Letters, VILLUM FONDEN 13261 28021, Independent Research Fund Denmark - European Union'sHorizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant 839090, National Science Foundation (NSF) AST-1911225, CONICYT PFCHA/DOCTORADOBECAS CHILE/2017-72180113, Spanish grant within the European Funds for Regional Development (FEDER) PGC2018-095317-B-C21, Instrument Centre for Danish Astrophysics (IDA), National Aeronautics & Space Administration (NASA) NN12AR55G 80NSSC18K0284 80NSSC18K1575, UK Research & Innovation (UKRI), Science & Technology Facilities Council (STFC), ANID -Millennium Science Initiative ICN12 009, Jenny and AnttiWihuri foundation, ANID BECAS/DOCTORADO NACIONAL 21202412 W19AN003

SOXS (Son Of X-Shooter) is a medium resolution (~4500) wide-band (0.35 - 2.0 µm) spectrograph which passed the Final Design Review in 2018. The instrument is planned to be installed at the NTT in La Silla and it is mainly composed by five different optomechanical subsystems (Common Path, NIR spectrograph, UV-VIS spectrograph, Camera, and Calibration) and other mechanical subsystems (Interface flange, Platform, cable corotator, and cooling). It is currently in the procurement and integration phase. In this paper we present the post-FDR modifications in the mechanical design due to the various iterations with the manufacturers and the actual procurement status. The last part describes the strategy used to keep under control the mechanical interfaces between the subsystems.

SOXS (Son Of X-Shooter) will be the new medium resolution (R~4500 for 1'' slit), high-efficiency, wide band spectrograph for the ESO NTT at La Silla, optimized for classification and follow-up of transient events. SOXS will simultaneously cover UV optical and NIR bands (0.35-2.00 micron) using two different arms and a pre-slit Common Path feeding system. The instrument will be also equipped by a Calibration Unit and an Acquisition Camera (AC) System. In this paper we present the final opto-mechanical design for the AC System and we describe its development status. The project is currently in manufacturing and integration phases., 8 pages, 8 figures, SPIE conference. arXiv admin note: text overlap with arXiv:1809.01526

SOXS is a new spectrograph for the New Technology Telescope (NTT), optimized for transient and variable objects, covering a wide wavelength range from 350 to 2000 nm. SOXS is equipped with a calibration unit that will be used to remove the instrument signatures and to provide wavelength calibration to the data. The calibration unit will employ seven calibration lamps: a quartz-tungsten-halogen and a deuterium lamp for the flat-field correction, a ThAr lamp and four pencil-style rare-gas lamps for the wavelength calibration. The light from the calibration lamps is injected into the spectrograph mimicking the f/11 input beam of the NTT, by using an integrating sphere and a custom doublet. The oversized illumination patch covers the length of the spectrograph slit homogeneously, with $< 1\%$ variation. The optics also supports the second mode of the unit, the star-simulator mode that emulates a point source by utilizing a pinhole mask. Switching between the direct illumination and pinhole modes is performed by a linear stage. A safety interlock switches off the main power when the lamp box cover is removed, preventing accidental UV exposure to the service personnel. All power supplies and control modules are located in an electronic rack at a distance from the telescope platform. In this presentation we describe the optical, mechanical, and electrical designs of the SOXS calibration unit, and report the status of development in which the unit is currently in the test and verification stage., 7 pages, 7 figures

We present here the development status of the NIR spectrograph of the Son Of X-Shooter (SOXS) instrument, for the ESO/NTT telescope at La Silla (Chile). SOXS is a R~4,500 mean resolution spectrograph, with a simultaneously coverage from about 0.35 to 2.00 μm. It will be mounted at the Nasmyth focus of the NTT. The two UV-VIS-NIR wavelength ranges will be covered by two separated arms. The NIR spectrograph is a fully cryogenic echelle-dispersed spectrograph, working in the range 0.80-2.00 μm, equipped with a Hawaii H2RG IR array from Teledyne. The whole spectrograph will be cooled down to about 150 K (but the array at 40 K), to lower the thermal background, and equipped with a thermal filter to block any thermal radiation above 2.0 μm. In this work, we will show the advanced phase of integration of the NIR spectrograph.

SOXS (Son Of X-Shooter) is a single object spectrograph, characterized by offering a wide simultaneous spectral coverage from U- to H-band, built by an international consortium for the 3.6-m ESO New Technology Telescope at the La Silla Observatory, in the Southern part of the Chilean Atacama Desert. The consortium is focussed on a clear scientific goal: the spectrograph will observe all kind of transient and variable sources discovered by different surveys with a highly flexible schedule, updated daily, based on the Target of Opportunity concept. It will provide a key spectroscopic partner to any kind of imaging survey, becoming one of the premier transient follow-up instruments in the Southern hemisphere. SOXS will study a mixture of transients encompassing all distance scales and branches of astronomy, including fast alerts (such as gamma-ray bursts and gravitational waves), mid-term alerts (such as supernovae and X-ray transients), and fixed-time events (such as the close-by passage of a minor planet or exoplanets). It will also have the scope to observe active galactic nuclei and blazars, tidal disruption events, fast radio bursts, and more. Besides of the consortium programs on guaranteed time, the instrument is offered to the ESO community for any kind of astrophysical target. The project has passed the Final Design Review and is currently in manufacturing and integration phase. This paper describes the development status of the project., Proc SPIE Volume 11447, Ground-based and Airborne Instrumentation for Astronomy VIII, 1144709,2020

SOXS (Son Of X-Shooter) is a forthcoming instrument for ESO-NTT, mainly dedicated to the spectroscopic study of transient events and is currently starting the AIT (Assembly, Integration, and Test) phase. It foresees a visible spectrograph, a near-Infrared (NIR) spectrograph, and an acquisition camera for light imaging and secondary guiding. The optimal setup and the monitoring of SOXS are carried out with a set of software-controlled motorized components and sensors. The instrument control software (INS) also manages the observation and calibration procedures, as well as maintenance and self-test operations. The architecture of INS, based on the latest release of the VLT Software (VLT2019), has been frozen; the code development is in an advanced state for what concerns supported components and observation procedures, which run in simulation. In this proceeding we present the INS current status, focusing in particular on the ongoing efforts in the support of two non-standard, "special" devices. The first special device is the piezoelectric slit exchanger for the NIR spectrograph; the second special device is the piezoelectric tip-tilt corrector used for active compensation of mechanical flexures of the instrument., 8 pages, 4 figures

The availability of updated model atmospheres for red supergiants and improvements in single and binary stellar evolution models, as well as previously unpublished data prompted us to revisit the progenitor of low-luminosity type II-Plateau supernova, SN 2008bk. Using mid-IR data in combination with dust models, we find that high temperature (4250-4500 K), high extinction (E(B-V)>0.7) solutions are incompatible with the data. We therefore favour a cool (~3500-3700 K) progenitor with a luminosity of log(L/Lsun)~4.53. Comparing with evolutionary tracks, we infer progenitor masses in the 8-10 Msun range in agreement with some previous studies. This mass is consistent with the observed pattern of low-luminosity Type IIP SNe coming from the explosion of RSGs at the lower extremum for core-collapse. We also present multi-epoch data of the progenitor, but do not find clear evidence of variability., 9 pages, 6 figures

The point spread function reconstruction (PSF-R) capability is a deliverable of the MICADO@ESO-ELT project. The PSF-R team works on the implementation of the instrument software devoted to reconstruct the point spread function (PSF), independently of the science data, using adaptive optics (AO) telemetry data, both for Single Conjugate (SCAO) and Multi-Conjugate Adaptive Optics (MCAO) mode of the MICADO camera and spectrograph. The PSF-R application will provide reconstructed PSFs through an archive querying system to restore the telemetry data synchronous to each science frame that MICADO will generate. Eventually, the PSF-R software will produce the output according to user specifications. The PSF-R service will support the state-of-the-art scientific analysis of the MICADO imaging and spectroscopic data., 10 pages, 2 figures. Proceeding of the SPIE conference Adaptive Optics Systems VII, SPIE Astronomical Telescopes + Instrumentation 2020 Digital Forum, 14-18 December 2020 (paper 11448-169)

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.--Full list of authors: Ackley, K.; Amati, L.; Barbieri, C.; Bauer, F. E.; Benetti, S.; Bernardini, M. G.; Bhirombhakdi, K.; Botticella, M. T.; Branchesi, M.; Brocato, E.; Bruun, S. H.; Bulla, M.; Campana, S.; Cappellaro, E.; Castro-Tirado, A. J.; Chambers, K. C.; Chaty, S.; Chen, T. -W.; Ciolfi, R.; Coleiro, A.; Copperwheat, C. M.; Covino, S.; Cutter, R.; D'Ammando, F.; D'Avanzo, P.; De Cesare, G.; D'Elia, V.; Della Valle, M.; Denneau, L.; De Pasquale, M.; Dhillon, V. S.; Dyer, M. J.; Elias-Rosa, N.; Evans, P. A.; Eyles-Ferris, R. A. J.; Fiore, A.; Fraser, M.; Fruchter, A. S.; Fynbo, J. P. U.; Galbany, L.; Gall, C.; Galloway, D. K.; Getman, F. I.; Ghirlanda, G.; Gillanders, J. H.; Gomboc, A.; Gompertz, B. P.; González-Fernández, C.; González-Gaitán, S.; Grado, A.; Greco, G.; Gromadzki, M.; Groot, P. J.; Gutiérrez, C. P.; Heikkilä, T.; Heintz, K. E.; Hjorth, J.; Hu, Y. -D.; Huber, M. E.; Inserra, C.; Izzo, L.; Japelj, J.; Jerkstrand, A.; Jin, Z. P.; Jonker, P. G.; Kankare, E.; Kann, D. A.; Kennedy, M.; Kim, S.; Klose, S.; Kool, E. C.; Kotak, R.; Kuncarayakti, H.; Lamb, G. P.; Leloudas, G.; Levan, A. J.; Longo, F.; Lowe, T. B.; Lyman, J. D.; Magnier, E.; Maguire, K.; Maiorano, E.; Mandel, I.; Mapelli, M.; Mattila, S.; McBrien, O. R.; Melandri, A.; Michałowski, M. J.; Milvang-Jensen, B.; Moran, S.; Nicastro, L.; Nicholl, M.; Nicuesa Guelbenzu, A.; Nuttal, L.; Oates, S. R.; O'Brien, P. T.; Onori, F.; Palazzi, E.; Patricelli, B.; Perego, A.; Torres, M. A. P.; Perley, D. A.; Pian, E.; Pignata, G.; Piranomonte, S.; Poshyachinda, S.; Possenti, A.; Pumo, M. L.; Quirola-Vásquez, J.; Ragosta, F.; Ramsay, G.; Rau, A.; Rest, A.; Reynolds, T. M.; Rosetti, S. S.; Rossi, A.; Rosswog, S.; Sabha, N. B.; Sagués Carracedo, A.; Salafia, O. S.; Salmon, L.; Salvaterra, R.; Savaglio, S.; Sbordone, L.; Schady, P.; Schipani, P.; Schultz, A. S. B.; Schweyer, T.; Smartt, S. J.; Smith, K. W.; Smith, M.; Sollerman, J.; Srivastav, S.; Stanway, E. R.; Starling, R. L. C.; Steeghs, D.; Stratta, G.; Stubbs, C. W.; Tanvir, N. R.; Testa, V.; Thrane, E.; Tonry, J. L.; Turatto, M.; Ulaczyk, K.; van der Horst, A. J.; Vergani, S. D.; Walton, N. A.; Watson, D.; Wiersema, K.; Wiik, K.; Wyrzykowski, Ł.; Yang, S.; Yi, S. -X.; Young, D. R., Context. Gravitational wave (GW) astronomy has rapidly reached maturity, becoming a fundamental observing window for modern astrophysics. The coalescences of a few tens of black hole (BH) binaries have been detected, while the number of events possibly including a neutron star (NS) is still limited to a few. On 2019 August 14, the LIGO and Virgo interferometers detected a high-significance event labelled S190814bv. A preliminary analysis of the GW data suggests that the event was likely due to the merger of a compact binary system formed by a BH and a NS. Aims. In this paper, we present our extensive search campaign aimed at uncovering the potential optical and near infrared electromagnetic counterpart of S190814bv. We found no convincing electromagnetic counterpart in our data. We therefore use our non-detection to place limits on the properties of the putative outflows that could have been produced by the binary during and after the merger. Methods. Thanks to the three-detector observation of S190814bv, and given the characteristics of the signal, the LIGO and Virgo Collaborations delivered a relatively narrow localisation in low latency - a 50% (90%) credible area of 5 deg2 (23 deg2) - despite the relatively large distance of 267 ± 52 Mpc. ElectromagNetic counterparts of GRAvitational wave sources at the VEry Large Telescope collaboration members carried out an intensive multi-epoch, multi-instrument observational campaign to identify the possible optical and near infrared counterpart of the event. In addition, the ATLAS, GOTO, GRAWITA-VST, Pan-STARRS, and VINROUGE projects also carried out a search on this event. In this paper, we describe the combined observational campaign of these groups. Results. Our observations allow us to place limits on the presence of any counterpart and discuss the implications for the kilonova (KN), which was possibly generated by this NS-BH merger, and for the strategy of future searches. The typical depth of our wide-field observations, which cover most of the projected sky localisation probability (up to 99.8%, depending on the night and filter considered), is r ∼ 22 (resp. K ∼ 21) in the optical (resp. near infrared). We reach deeper limits in a subset of our galaxy-targeted observations, which cover a total ∼50% of the galaxy-mass-weighted localisation probability. Altogether, our observations allow us to exclude a KN with large ejecta mass M 0.1 M- to a high (> 90%) confidence, and we can exclude much smaller masses in a sub-sample of our observations. This disfavours the tidal disruption of the neutron star during the merger. Conclusions. Despite the sensitive instruments involved in the campaign, given the distance of S190814bv, we could not reach sufficiently deep limits to constrain a KN comparable in luminosity to AT 2017gfo on a large fraction of the localisation probability. This suggests that future (likely common) events at a few hundred megaparsecs will be detected only by large facilities with both a high sensitivity and large field of view. Galaxy-targeted observations can reach the needed depth over a relevant portion of the localisation probability with a smaller investment of resources, but the number of galaxies to be targeted in order to get a fairly complete coverage is large, even in the case of a localisation as good as that of this event. © K. Ackley et al. 2020., Based on observations collected at the European Southern Observatory under ESO programmes 1102.D-0353(E), 1102.D0353(F), 1102.D-0353(Q), 1102.D-0353(G), 0103.D-0070(A), 0103.D-0070(B), 0103.D-0703(A), 0103.D-0722(A), 0103.A-9099(A), 198.D-2010(D) and 60.A9285(A). ATLAS is primarily funded through NEO NASA grants NN12AR55G, 80NSSC18K0284, and 80NSSC18K1575. The ATLAS science products have been made possible through the contributions of the University of Hawaii IfA, the Queen's University Belfast, the Space Telescope Science Institute, and the South African Astronomical Observatory. PanSTARRS is primarily funded through NEO NASA grants NASA Grants NNX08AR22G, NNX14AM74G. The PanSTARRS science products for LIGO-Virgo follow-up are made possible through the contributions of the University of Hawaii IfA and the Queen's University Belfast. The Gravitational-wave Optical Transient Observer (GOTO) project acknowledges the support of the Monash-Warwick Alliance; Warwick University; Monash University; She ffield University; Leicester University; Armagh Observatory & Planetarium; the National Astronomical Research Institute of Thailand (NARIT); University of Portsmouth; Turku University and the Instituto de Astrofisica de Canarias (IAC). Part of the funding for GROND was generously granted from the Leibniz-Prize to Prof. G. Hasinger (DFG grant HA 1850/28-1). The Liverpool Telescope is operated on the island of La Palma by Liverpool John Moores University in 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. The WHT and its override programme are operated on the island of La Palma by the Isaac Newton Group of Telescopes in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias; part of these data were taken under program (19A)N3. FEB thanks CONICYT Basal AFB-170002 and Chile's Ministry of Economy fund IC120009. MGB, PDA and AM acknowledge support from ASI grant I/004/11/3. MBr, EC, AP and SPi acknowledge support from MIUR (PRIN 2017 grant 20179ZF5KS). EB, EM and MT acknowledge funding from GRAWITA. SHB is indebted to the Danish National Research Foundation (DNRF132) for support. SCa acknowledges support from grant MAE0065741. EC acknowledges the support of the H2020 OPTICON programme 730890. TWC acknowledges the Humboldt Foundation and Marie Sklodowska-Curie grant 842471. MDP thanks Istanbul University for support. PAE acknowledges UKSA support. RAJEF is supported by an STFC studentship. MF is supported by a Royal Society -SFI University Research Fellowship. LG was funded by the EU H2020 programme under MSCA grant no. 839090. CG, JH and LI were supported by a research grant from VILLUM FONDEN (project 16599). CG and LI were supported by a research grant from VILLUM FONDEN (25501). GGh acknowledges the PRIN MIUR "Figaro" for financial support. AGo acknowledges financial support from the Slovenian Research Agency (grants P1-0031, I0-0033, and J1-8136). BPG, AJL and JDL acknowledge support from ERC grant 725246 (TEDE, PI Levan). SGG acknowledges support by FCT Fundacao para a Ciencia e Tecnologia and by Project PTDC/FIS-AST-31546. GGr acknowledges the ESCAPE H2020 project no. 824064. MG is supported by the Polish NCN MAESTRO grant 2014/14/A/ST9/00121. PJG acknowledges support from NOVA and from the South African NRF SARChI grant 111692. CPG and MS acknowledge support from EU/FP7-ERC grant no. 615929. KEH acknowledges support by a Project Grant from The Icelandic Research Fund. YDH acknowledges support from the China Scholarships Council. JJ acknowledges support from NOVA and NWO-FAPESP grant for instrumentation. AJ acknowledges funding from the European Research Council (ERC). ZPJ was supported by the Foundation for Distinguished Young Scholars of Jiangsu Province (no. BK20180050). PGJ acknowledges funding from the ERC under Consolidator Grant agreement no. 647208. DAK acknowledges Spanish research project RTI2018-098104-J-I00 (GRBPhot). SKl acknowledges support by DFG grant Kl 766/16-3. ECK acknowledges support from the GREAT research environment. GPL acknowledges support from STFC via grant ST/N000757/1. GL was supported by a research grant (19054) from VILLUM FONDEN. KM acknowledges support from the ERC (grant no. 758638). IM is partially supported by OzGrav (ARC project CE17010000). MMacknowledges support from ERC through ERC-2017-CoG no. 770017. MJM acknowledges the National Science Centre, Poland, grant 2018/30/E/ST9/00208. BMJ and DW are supported by Independent Research Fund Denmark grant DFF-7014-00017. MN is supported by a Royal Astronomical Society Research Fellowship. ANG acknowledges support by grant DFG Kl 766/16-3. PTOB acknowledges funding from STFC. SRO gratefully acknowledges the support of the Leverhulme Trust. FO acknowledges the support of the H2020 Hemera program, grant no. 730970. MAPT was supported by grants RYC-2015-17854 and AYA201783216-P. EP aknowledges financial support from INAF. GP is supported by the Millennium Science Initiative through grant IC120009. MLP is partially supported by a "Linea 2" project of the Catania University. JQV acknowledges support from CONICYT folio 21180886. TMR acknowledges the support of the Vilho, Yrjo and Kalle Vaisala Foundation. ARo acknowledges support from Premiale LBT 2013. SR is supported by VR grants 2016-03657_3 and the research environment grant GREAT, Dnr. 2016-06012, and the Swedish National Space board, Dnr. 107/16. OSS acknowledges the Italian Ministry of Research (MIUR) grant 1.05.06.13. LSa acknowledges the Irish Research Council Scholarship no. GOIPG/2017/1525. SJS acknowledges support from STFC Grant ST/P000312/1. ERS and DS acknowledge funding from UK STFC CG ST/P000495/1. RLCS acknowledges funding from STFC. DS acknowledges support from STFC via grant ST/T007184/1. SDV acknowledges the support of the CNES. LWsupported by Polish NCN DAINA 2017/27/L/ST9/03221. The Cosmic DAWN center is funded by the Danish National Research Foundation.

Nearby galaxies offer unique laboratories allowing multi-wavelength spatially resolved studies of the interstellar medium, star formation and nuclear activity across a broad range of physical conditions. In particular, detailed studies of individual local luminous infrared galaxies (LIRGs) are crucial for gaining a better understanding of these processes and for developing and testing models that are used to explain statistical studies of large populations of such galaxies at high redshift for which it is currently impossible to reach a sufficient physical resolution. Here, we provide an overview of the impact of spatially resolved infrared, sub-millimetre and radio observations in the study of the interstellar medium, star formation and active galactic nuclei as well as their interplay in local LIRGs. We also present an overview of the modelling of their spectral energy distributions using state-of-the-art radiative transfer codes. These contribute necessary and powerful ‘workhorse’ tools for the study of LIRGs (and their more luminous counterparts) at higher redshifts which are unresolved in observations. We describe how spatially-resolved time-domain observations have recently opened a new window to study the nuclear activity in LIRGs. We describe in detail the observational characteristics of Arp 299 which is one of the best studied local LIRGs and exemplifies the power of the combination of time-domain and high-resolution observations at infrared to radio wavelengths together with radiative transfer modelling used to explain the spectral energy distributions of its different components. We summarise the previous achievements obtained using high-spatial resolution observations and provide an outlook into what we can expect to achieve with future facilities. © 2021, Springer-Verlag GmbH Germany, part of Springer Nature., MPT acknowledges financial support from the State Agency for Research of the Spanish MCIU through the Center of Excellence Severo Ochoa award to the Instituto de Astrofi ' sica de Andaluci ' a (SEV-2017-0709) and through grant PGC2018-098915-B-C21 (MCI/AEI/FEDER, UE) as well as from the visitor and mobility program of the Finnish Centre for Astronomy with ESO (FINCA), funded by the Academy of Finland grant nr 306531. AA-H acknowledges support through grant PGC 2018-094671-BI00 (MCIU/AEI/FEDER, UE). AA-H work was done under project No. MDM-2017-0737 Unidad de Excelencia "Maria de Maeztu'' - Centro de Astrobiologia (INTA-CSIC). SA gratefully acknowledges support from an ERC Advanced Grant 789410 and from the Swedish Research Council. AE acknowledges support from the Cyprus Research & Innovation Foundation (GRATOS; EXCELLENCE/1216/0207) and the European Space Agency (CYGNUS; ESA contract 400126896/19/NL/MH).

We present the discovery with Keck of the extremely infrared (IR) luminous transient AT 2017gbl, coincident with the Northern nucleus of the luminous infrared galaxy (LIRG) IRAS 23436+5257. Our extensive multiwavelength follow-up spans similar to 900 d, including photometry and spectroscopy in the optical and IR, and (very long baseline interferometry) radio and X-ray observations. Radiative transfer modelling of the host galaxy spectral energy distribution and long-term pre-outburst variability in the mid-IR indicate the presence of a hitherto undetected dust obscured active galactic nucleus (AGN). The optical and near-IR spectra show broad similar to 2000 km s(-1) hydrogen, He I, and OI emission features that decrease in flux over time. Radio imaging shows a fast evolving compact source of synchrotron emission spatially coincident with AT 2017gbl. We infer a lower limit for the radiated energy of 7.3 x 10(50) erg from the IR photometry. An extremely energetic supernova would satisfy this budget, but is ruled out by the radio counterpart evolution. Instead, we propose AT 2017gbl is related to an accretion event by the central supermassive black hole, where the spectral signatures originate in the AGN broad line region and the IR photometry is consistent with re-radiation by polar dust. Given the fast evolution of AT 2017gbl, we deem a tidal disruption event (TDE) of a star a more plausible scenario than a dramatic change in the AGN accretion rate. This makes AT 2017gbl the third TDE candidate to be hosted by a LIRG, in contrast to the so far considered TDE population discovered at optical wavelengths and hosted preferably by post-starburst galaxies., ECKacknowledges support from the Gravitational Radiation and Electromagnetic Astrophysical Transients (GREAT) research environment funded by Vetenskapsradet under project no. 2016-06012, financial support from the visitor and mobility program of the Finnish Centre for Astronomy with ESO (FINCA), funded by the Academy of Finland grant no. 306531, and support from The Wenner-Gren Foundations under project no. UPD2019-0070. TMR acknowledges the financial support of the Jenny and Antti Wihuri foundation and the Vilho, Yrjo and Kalle Vaisala Foundation of the Finnish Academy of Science and Letters. MPT acknowledges financial support from the State Agency for Research of the Spanish MCIU through the 'Center of Excellence Severo Ochoa' award to the Instituto de Astrofisica de Andaluc ' ia (SEV-2017-0709) and through grant PGC2018-098915-B-C21 (MCI/AEI/FEDER). CRC acknowledges support by the Chinese Academy of Sciences (CAS), through grant CAS16013 of the CAS South America Center for Astronomy (CASSACA) and Programa de Astronomia CONICYT, Chile. PGJ and GC acknowledge support from European Research Council Consolidator Grant 647208. MG is supported by the Polish NCN MAESTRO grant 2014/14/A/ST9/00121. GEA is the recipient of an Australian Research Council Discovery Early Career Researcher Award (project DE180100346) and acknowledges partial support through the Australian Research Council's Discovery Projects funding scheme (project DP200102471). ST acknowledges financial support from the Russian Foundation for Basic Research project 1752-80139 BRICS-a. RMcD is the recipient of an Australian Research Council Future Fellowship Award (project number FT150100333). WL is supported by the David and Ellen Lee Fellowship at Caltech. The NOT Unbiased Transient Survey 2 (NUTS2) is funded in part by the Instrument Center for Danish Astronomy. Some of the data (PI: S. Ryder; program IDs Z229N2L, Z271N2L) 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 authorswish 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. We thank the Mullard Radio Astronomy Observatory for carrying out the AMI-LA observations. Thiswork is based in part on observations (PIs: E. Kool, K. Maeda; program IDs GN-2017B-DD-2, GN-2018B-FT-109) obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), National Research Council (Canada), CONICYT (Chile), Ministerio de Ciencia, Tecnologia e Innovacion Productiva (Argentina), Ministerio da Ciencia, Tecnologia e Inovacao (Brazil), and Korea Astronomy and Space Science Institute (Republic of Korea). The scientific results reported in this article are based in part on observations (PI: T. Heikkila; program ID 18208589) made by the Chandra X-ray Observatory, and this research has made use of the CIAO software package provided by the ChandraX-rayCenter (CXC). This article includes results based on observations made by the Neil Gehrels Swift observatory. The authors thank Chandra and Swift teams for the approval and rapid scheduling of our observations. This work is based in part on observations made with theWilliam Herschel Telescope (WHT). The WHT is operated on the island of La Palma by the Isaac Newton Group of Telescopes in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. The ISIS and ACAM data were obtained as part of (17A)N4/N6, (18A)N4, and (18B)N5. This work is based in part on observations (PI: S. Mattila; program IDs 13226, 14054) made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. This publication makes use of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration. This publication also makes use of data products from NEOWISE, which is a project of the Jet Propulsion Laboratory/California Institute of Technology, funded by the Planetary Science Division of the National Aeronautics and Space Administration. This work is based in part on observations from programs RP028B and BP225 (PI: M. Perez-Torres) obtained with the European VLBI Network (EVN) and the Very Long Baseline Array (VLBA), respectively. The European VLBI Network is a joint facility of independent European, African, Asian, and North American radio astronomy institutes. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. Funding for the SDSS and SDSS-II has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the U.S. Department of Energy, the National Aeronautics and Space Administration, the Japanese Monbukagakusho, theMax Planck Society, and the Higher Education Funding Council for England. The SDSS Web Site is http://www.sdss.org/. The SDSS is managed by the Astrophysical Research Consortium for the Participating Institutions. The Participating Institutions are the American Museum of Natural History, Astrophysical Institute Potsdam, University of Basel, University of Cambridge, Case Western Reserve University, University of Chicago, Drexel University, Fermilab, the Institute for Advanced Study, the Japan Participation Group, Johns Hopkins University, the Joint Institute for Nuclear Astrophysics, the Kavli Institute for Particle Astrophysics and Cosmology, the Korean Scientist Group, the Chinese Academy of Sciences (LAMOST), Los Alamos National Laboratory, the MaxPlanck-Institute for Astronomy (MPIA), the Max-Planck-Institute for Astrophysics (MPA), New Mexico State University, Ohio State University, University of Pittsburgh, University of Portsmouth, Princeton University, the United States Naval Observatory, and the University of Washington.

arXiv:1905.02205v2, et al., We report observations of the hydrogen-deficient supernova (SN) 2019bkc/ATLAS19dqr. With B- and r-band decline between peak and 10 days post peak of ${\rm{\Delta }}{m}_{10}(B)=5.24\pm 0.07$ mag and ${\rm{\Delta }}{m}_{10}(r)=3.85\pm 0.10$ mag, respectively, SN 2019bkc is the most rapidly declining SN I discovered so far. While its closest matches are the rapidly declining SN 2005ek and SN 2010X, the light curves and spectra of SN 2019bkc show some unprecedented characteristics. SN 2019bkc appears "hostless," with no identifiable host galaxy near its location, although it may be associated with the galaxy cluster MKW1 at z = 0.02. We evaluate a number of existing models of fast-evolving SNe, and we find that none of them can satisfactorily explain all aspects of SN 2019bkc observations., We acknowledge SUPA2019A-002 (PI: M.D. Stritzinger) via OPTICON. M.S. and S.H. are supported by a project grant (8021-00170B) from the IRF, Denmark and a grant (13261) from VILLUM FONDEN. J.S. acknowledges support from the Packard Foundation. C.S.K. is supported by NSF grants AST-1515876, AST-1515927 and AST-1814440, as well as a fellowship from the Radcliffe Institute for Advanced Study at Harvard University. E.W.P. acknowledges NSFC. 11573002. E.A. acknowledges NSF grant AST-1751874. D.A.H.B. acknowledges South African National Research Foundation. M.G. is supported by the Polish NCN MAESTRO grant 2014/14/A/ ST9/00121. K.D.F. is supported by Hubble Fellowship grant HST-HF2-51391.001-A. S.B. is partially supported by the PRININAF 2016 (PI: M. Giroletti) S.B. and A.A.S. acknowledge NSF grant AST-1814719. N.E.R. acknowledges Spanish MICINN grant ESP2017-82674-R and FEDER funds.

We present observations of the unusually luminous Type II supernova (SN) 2016gsd. With a peak absolute magnitude of V = -19.95 ± 0.08, this object is one of the brightest Type II SNe, and lies in the gap of magnitudes between the majority of Type II SNe and the superluminous SNe. Its light curve shows little evidence of the expected drop from the optically thick phase to the radioactively powered tail. The velocities derived from the absorption in H α are also unusually high with the blue edge tracing the fastest moving gas initially at 20 000 km s-1, and then declining approximately linearly to 15 000 km s-1 over ∼100 d. The dwarf host galaxy of the SN indicates a low-metallicity progenitor which may also contribute to the weakness of the metal lines in its spectra. We examine SN 2016gsd with reference to similarly luminous, linear Type II SNe such as SNe 1979C and 1998S, and discuss the interpretation of its observational characteristics. We compare the observations with a model produced by the jekyll code and find that a massive star with a depleted and inflated hydrogen envelope struggles to reproduce the high luminosity and extreme linearity of SN 2016gsd. Instead, we suggest that the influence of interaction between the SN ejecta and circumstellar material can explain the majority of the observed properties of the SN. The high velocities and strong H α absorption present throughout the evolution of the SN may imply a circumstellar medium configured in an asymmetric geometry., MF acknowledges the support of a Royal Society – Science Foundation Ireland University Research Fellowship. The JEKYLL simulations were performed on resources provided by the Swedish National Infrastructure for Computing (SNIC) at Parallelldatorcentrum (PDC). PL acknowledges support from the Swedish Research Council. MS is supported by a generous grant (13261) from Villum Fonden and a project grant (8021-00170B) from the Independent Research Fund Denmark (IRFD). NUTS2 is funded in part by the Instrument Center for Danish Astronomy (IDA). This work is based (in part) on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile as part of PESSTO (the Public ESO Spectroscopic Survey for Transient Objects) ESO program 188.D−3003, 191.D−0935, more ESO acknowledgements. The Pan-STARRS1 Surveys (PS1) and the PS1 public science archive have been made possible through contributions by 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, the Queen’s University Belfast, the Harvard-Smithsonian Center for Astrophysics, the Las Cumbres Observatory Global Telescope Network Incorporated, the National Central University of Taiwan, the Space Telescope Science Institute, the National Aeronautics and Space Administration under Grant No. NNX08AR22G issued through the Planetary Science Division of the NASA Science Mission Directorate, the National Science Foundation Grant No. AST−1238877, the University of Maryland, Eotvos Lorand University (ELTE), the Los Alamos National Laboratory, and the Gordon and Betty Moore Foundation. The SCUSS is funded by the Main Direction Program of Knowledge Innovation of Chinese Academy of Sciences (No. KJCX2−EW−T06). It is also an international cooperative project between National Astronomical Observatories, Chinese Academy of Sciences, and Steward Observatory, University of Arizona, USA. Technical support and observational assistance from the Bok telescope are provided by Steward Observatory. The project is managed by the National Astronomical Observatory of China and Shanghai Astronomical Observatory. Data resources are supported by Chinese Astronomical Data Center (CAsDC). SD and PC 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. SJS acknowledges STFC grant ST/P000312/1. This work has made use of data from the Asteroid Terrestial-impact Last Alert System (ATLAS) Project. ATLAS is primarily funded to search for near earth asteroids through NASA grants NN12AR55G, 80NSSC18K0284, and 80NSSC18K1575; byproducts of the NEO search include images and catalogues from the survey area. The ATLAS science products have been made possible through the contributions of the University of Hawaii Institute for Astronomy, the Queen’s Univeristy Belfast, the Space Telescope Science Institute, and the South African Astronomical Observatory. OR acknowledges support by projects IC120009 ‘Millennium Institute of Astrophysics (MAS)’ of the Iniciativa Científica Milenio del Ministerio de Economía, Fomento y Turismo de Chile and CONICYT PAI/INDUSTRIA 79090016. JH acknowledges financial support from the Finnish Cultural Foundation. Some data were taken with the Las Cumbres Observatory Network. GH and DAH are supported by NSF grant AST-1313484. GH 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. LG was funded by the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 839090. This work also makes use of observations collected at the European Southern Observatory under ESO programme 0103.D-0338(A). CPG acknowledges support from EU/FP7-ERC grant no. [615929].

The forthcoming SOXS (Son Of X-Shooter) will be a new spectroscopic facility for the ESO New Technology Telescope in La Silla, focused on transient events and able to cover both the UV-VIS and NIR bands. The instrument passed the Final Design Review in 2018 and is currently in manufacturing and integration phase. This paper is focused on the assembly and testing of the instrument control electronics, which will manage all the motorized functions, alarms, sensors, and electric interlocks. The electronics is hosted in two main control cabinets, divided in several subracks that are assembled to ensure easy accessibility and transportability, to simplify test, integration and maintenance. Both racks are equipped with independent power supply distribution and have their own integrated cooling systems. This paper shows the assembly strategy, reports on the development status and describes the tests performed to verify the system before the integration into the whole instrument.

Spectral observations of the type-IIb supernova (SN) 2016gkg at 300-800 days are reported. The spectra show nebular characteristics, revealing emission from the progenitor star's metal-rich core and providing clues to the kinematics and physical conditions of the explosion. The nebular spectra are dominated by emission lines of [O i] λλ6300, 6364 and [Ca ii] λλ7292, 7324. Other notable, albeit weaker, emission lines include Mg I] λ4571, [Fe ii] λ7155, O I λ7774, Ca II triplet, and a broad, boxy feature at the location of Hα. Unlike in other stripped-envelope SNe, the [O i] doublet is clearly resolved due to the presence of strong narrow components. The doublet shows an unprecedented emission line profile consisting of at least three components for each [O i]λ6300, 6364 line: a broad component (width ∼2000 km s⁻¹), and a pair of narrow blue and red components (width ∼300 km s⁻¹) mirrored against the rest velocity. The narrow component appears also in other lines, and is conspicuous in [O i]. This indicates the presence of multiple distinct kinematic components of material at low and high velocities. The low-velocity components are likely to be produced by a dense, slow-moving emitting region near the center, while the broad components are emitted over a larger volume. These observations suggest an asymmetric explosion, supporting the idea of two-component ejecta that influence the resulting late-time spectra and light curves. SN 2016gkg thus presents striking evidence for significant asymmetry in a standard-energy SN explosion. The presence of material at low velocity, which is not predicted in 1D simulations, emphasizes the importance of multidimensional explosion modeling of SNe., Facultad de Ciencias Astronómicas y Geofísicas, Instituto de Astrofísica de La Plata

Son Of X-Shooter (SOXS) is a double-armed (UV-VIS, NIR) spectrograph designed to be mounted at the ESO-NTT in La Silla, now in its Assembly Integration and Verification (AIV) phase. The instrument is designed following a modular approach so that each sub-system can be integrated in parallel before their assembly at system level. INAF-Osservatorio Astronomico di Padova will deliver the Common Path (CP) sub-system, which represents the backbone of the entire instrument. In this paper, we describe the foreseen operation for the CP alignment and we report some results already achieved, showing that we envisaged the suitable setup and the strategy to meet the opto-mechanical requirements.

Full author list: L. Tartaglia, A. Pastorello, J. Sollerman, C. Fransson, S. Mattila, M. Fraser, F. Taddia, L. Tomasella, M. Turatto, A. Morales-Garoffolo, N. Elias-Rosa, P. Lundqvist, J. Harmanen, T. Reynolds, E. Cappellaro, C. Barbarino, A. Nyholm, E. Kool, E. Ofek, X. Gao, Z. Jin, H. Tan, D. J. Sand, F. Ciabattari, X. Wang, J. Zhang, F. Huang, W. Li, J. Mo, L. Rui, D. Xiang, T. Zhang, G. Hosseinzadeh, D. A. Howell, C. McCully, S. Valenti, S. Benetti, E. Callis, A. S. Carracedo, C. Fremling, T. Kangas, A. Rubin, A. Somero and G. Terreran, In this paper we report the results of the first ~four years of spectroscopic and photometric monitoring of the Type IIn supernova SN 2015da (also known as PSN J13522411+3941286, or iPTF16tu). The supernova exploded in the nearby spiral galaxy NGC 5337 in a relatively highly extinguished environment. The transient showed prominent narrow Balmer lines in emission at all times and a slow rise to maximum in all bands. In addition, early observations performed by amateur astronomers give a very well-constrained explosion epoch. The observables are consistent with continuous interaction between the supernova ejecta and a dense and extended H-rich circumstellar medium. The presence of such an extended and dense medium is difficult to reconcile with standard stellar evolution models, since the metallicity at the position of SN 2015da seems to be slightly subsolar. Interaction is likely the mechanism powering the light curve, as confirmed by the analysis of the pseudo bolometric light curve, which gives a total radiated energy ≳ 1051 erg. Modeling the light curve in the context of a supernova shock breakout through a dense circumstellar medium allowed us to infer the mass of the prexisting gas to be ≂ 8 MO , with an extreme mass-loss rate for the progenitor star ≂ 0.6 MO yr-1, suggesting that most of the circumstellar gas was produced during multiple eruptive events. Near- and mid-infrared observations reveal a fluxexcess in these domains, similar to those observed in SN 2010jl and other interacting transients, likely due to preexisting radiatively heated dust surrounding the supernova. By modeling the infrared excess, we infer a mass ≳ 0.4 × 10-3 MO for the dust., The Oskar Klein Centre is funded by the Swedish Research Council. We acknowledge the support of the staff of the Xinglong 2.16 m telescope. This work was partially supported by the Open Project Program of the Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences. M.F. is supported by a Royal Society – Science Foundation Ireland University Research Fellowship. J.H. acknowledges financial support from the Finnish Cultural Foundation and the Vilho, Yrjö and Kalle Väisälä Foundation of the Finnish Academy of Science and Letters. Research by D.J.S. is supported by NSF grants AST-1821987, AST-1821967, AST-1813708, AST-1813466 and AST-1908972. S.B., L.T.and M.T. are partially supported by the PRIN-INAF 2016 with the project “Towards the SKA and CTA era: discovery, localisation, and physics of transient sources” (PI: M. Giroletti). N E.-R. acknowledges support from the Spanish MICINN grant ESP2017–82674–R and FEDER funds. D.A.H., C.M., and G.H. were supported by NSF AST-1313484 The work of X.W. is supported by the National Natural Science Foundation of China (NSFC grants 11325313, 11633002, and 11761141001), and the National Program on Key Research and Development Project (grant no. 2016YFA0400803). Research by S.V. is supported by NSF grant AST-1813176. J.Z. is supported by the National Natural Science Foundation of China (NSFC, grants 11773067, 11403096), the Youth Innovation Promotion Association of the CAS (grants 2018081), and the Western Light Youth Project. Based on observations collected at: ESO La Silla Observatory under program “Optical & NIR monitoring of bright supernovae with REM” during AOT30. The Gemini Observatory, under program GN– 2016B-Q-57, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina), and Ministério da Ciência, Tecnologia e Inovação (Brazil). Tthe Nordic Optical Telescope, operated by the Nordic Optical Telescope Scientific Association and the Gran Telescopio Canarias (GTC), both installed at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofìsica de Canarias, on the island of La Palma (Spain). The Copernico Telescope (Asiago, Italy) operated by INAF – Osservatorio Astronomico di Padova. The 3 m Shane Reflector, located at the Lick Observatory (7281 Mt Hamilton Rd, Mt Hamilton, CA 95140, USA.) owned and operated by the University of California. This work makes use of observations from the Las Cumbres Observatory network of telescopes. We acknowledge the support of the staff of the Li–Jiang 2.4 m telescope (LJT). Funding for the LJT has been provided by the Chinese Academy of Sciences (CAS) and the People’s Government of Yunnan Province. The LJT is jointly operated and administrated by Yunnan Observatories and Center for Astronomical Mega–Science, CAS. This research has made use of the Keck Observatory Archive (KOA), which is operated by the W. M. Keck Observatory and the NASA Exoplanet Science Institute (NExScI), under contract with the National Aeronautics and Space Administration. 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 Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. This publication makes use of data products from NEOWISE, which is a project of the Jet Propulsion Laboratory/California Institute of Technology, founded by the Planetary Science Division of the National Aeronautics and Space Administration. This research has made use of the Keck Observatory Archive (KOA), which is operated by the W. M. Keck Observatory and the NASA Exoplanet Science Institute (NExScI), under contract with the National Aeronautics and Space Administration. 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. This research has made use of the NASA/IPAC Infrared Science Archive, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. Funding for the Sloan Digital Sky Survey (SDSS) has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Aeronautics and Space Administration, the National Science Foundation, the U.S. Department of Energy, the Japanese Monbukagakusho, and the Max Planck Society. The SDSS Web site is http://www.sdss.org/. This publication makes use of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration. The SDSS is managed by the Astrophysical Research Consortium (ARC) for the Participating Institutions. The Participating Institutions are The University of Chicago, Fermilab, the Institute for Advanced Study, the Japan Participation Group, The Johns Hopkins University, Los Alamos National Laboratory, the Max-Planck-Institute for Astronomy (MPIA), the Max-Planck-Institute for Astrophysics (MPA), New Mexico State University, University of Pittsburgh, Princeton University, the United States Naval Observatory, and the University of Washington. The intermediate Palomar Transient Factory project is a scientific collaboration among the California Institute of Technology, Los Alamos National Laboratory, the University of Wisconsin, Milwaukee, the Oskar Klein Center, the Weizmann Institute of Science, the TANGO Program of the University System of Taiwan, and the Kavli Institute for the Physics and Mathematics of the Universe. IRAF is distributed by the National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation. SNOOPY is a package for SN photometry using PSF fitting and/or template subtraction developed by E. Cappellaro. A package description can be found at http:// sngroup.oapd.inaf.it/snoopy.html. FOSCGUI is a graphic user interface aimed at extracting SN spectroscopy and photometry obtained with FOSC-like instruments. It was developed by E. Cappellaro. A package description can be found at http://sngroup.oapd.inaf.it/foscgui.html

In this work, we present photometric and spectroscopic data of the low-luminosity Type IIP supernova (SN) 2018hwm. The object shows a faint ($M_r=-15$ mag) and very long ($\sim$130 days) plateau, followed by a 2.7 mag drop in the $r$-band to the radioactive tail. The first spectrum shows a blue continuum with narrow Balmer lines, while during the plateau the spectra show numerous metal lines, all with strong and narrow P-Cygni profiles. The expansion velocities are low, in the 1000-1400 km s$^{-1}$ range. The nebular spectrum, dominated by H$\alpha$ in emission, reveals weak emission from [O I] and [Ca II] doublets. The absolute light curve and spectra at different phases are similar to those of low-luminosity SNe IIP. We estimate that 0.0085 $M_{\odot}$ of $^{56}$Ni mass were ejected, through hydrodynamical simulations. The best fit of the model to the observed data is found for an extremely low explosion energy of 0.075 foe, a progenitor radius of 845 $R_{\odot}$ and a final progenitor mass of 9-10 $M_{\odot}$. Finally, we performed a modeling of the nebular spectrum, to establish the amount of oxygen and calcium ejected. We found a low M($^{16}$O)$\approx 0.02$ $M_{\odot}$, but a high M($^{40}$Ca) of 0.3 $M_{\odot}$. The inferred low explosion energy, the low ejected $^{56}$Ni mass and the progenitor parameters, along with peculiar features observed in the nebular spectrum, are consistent with both an electron-capture SN explosion of a super-asymptotic giant branch star and with a low-energy, Ni-poor iron core-collapse SN from a 10-12 $M_{\odot}$ red supergiant., Comment: 15 pages, 8 figures, 6 tables, updated the progenitor parameters after the submission of an Erratum

The amount of observational data produced by time-domain astronomy is exponentially in-creasing. Human inspection alone is not an effective way to identify genuine transients fromthe data. An automatic real-bogus classifier is needed and machine learning techniques are commonly used to achieve this goal. Building a training set with a sufficiently large number of verified transients is challenging, due to the requirement of human verification. We presentan approach for creating a training set by using all detections in the science images to be thesample of real detections and all detections in the difference images, which are generated by the process of difference imaging to detect transients, to be the samples of bogus detections. This strategy effectively minimizes the labour involved in the data labelling for supervised machine learning methods. We demonstrate the utility of the training set by using it to train several classifiers utilizing as the feature representation the normalized pixel values in 21-by-21pixel stamps centered at the detection position, observed with the Gravitational-wave Optical Transient Observer (GOTO) prototype. The real-bogus classifier trained with this strategy can provide up to 95% prediction accuracy on the real detections at a false alarm rate of 1%., 9 pages, 8 figures

We present our progress on the UV-VIS arm of Son Of X-Shooter (SOXS), a new spectrograph for the NTT. Our design splits the spectral band into four sub-bands that are imaged onto a single detector. Each band uses an optimized high efficiency grating that operates in 1st order (m=1). In our previous paper we presented the concept and preliminary design. SOXS passed a Final Design Review in July 2018 and is well into the construction phase. Here we present the final design, performances of key manufactured elements, and the progress in the assembly. Based on the as-built elements, the expected throughput of the visual arm will be > 55%. This paper is accompanied by a series of contributions describing the progress made on the SOXS instrument.

We present the development of the End-to-End simulator for the SOXS instrument at the ESO-NTT 3.5-m telescope. SOXS will be a spectroscopic facility, made by two arms high efficiency spectrographs, able to cover the spectral range 350-2000 nm with resolving power R˜4500. The E2E model allows to simulate the propagation of photons starting from the scientific target of interest up to the detectors. The outputs of the simulator are synthetic frames, which will be mainly exploited for optimizing the pipeline development and possibly assisting for proper alignment and integration phases in laboratory and at the telescope. In this paper, we will detail the architecture of the simulator and the computational model, which are strongly characterized by modularity and flexibility. Synthetic spectral formats, related to different seeing and observing conditions, and calibration frames to be ingested by the pipeline are also presented.

We report the results of optical follow-up observations of 29 gravitational-wave triggers during the first half of the LIGO-Virgo Collaboration (LVC) O3 run with the Gravitational-wave Optical Transient Observer (GOTO) in its prototype 4-telescope configuration (GOTO-4). While no viable electromagnetic counterpart candidate was identified, we estimate our 3D (volumetric) coverage using test light curves of on- and off-axis gamma-ray bursts and kilonovae. In cases where the source region was observable immediately, GOTO-4 was able to respond to a GW alert in less than a minute. The average time of first observation was $8.79$ hours after receiving an alert ($9.90$ hours after trigger). A mean of $732.3$ square degrees were tiled per event, representing on average $45.3$ per cent of the LVC probability map, or $70.3$ per cent of the observable probability. This coverage will further improve as the facility scales up alongside the localisation performance of the evolving gravitational-wave detector network. Even in its 4-telescope prototype configuration, GOTO is capable of detecting AT2017gfo-like kilonovae beyond 200~Mpc in favourable observing conditions. We cannot currently place meaningful electromagnetic limits on the population of distant ($\hat{D}_L = 1.3$~Gpc) binary black hole mergers because our test models are too faint to recover at this distance. However, as GOTO is upgraded towards its full 32-telescope, 2 node (La Palma \& Australia) configuration, it is expected to be sufficiently sensitive to cover the predicted O4 binary neutron star merger volume, and will be able to respond to both northern and southern triggers., 15 pages, 7 figures, 3 tables. Accepted for publication in MNRAS. Author's final submitted version