The Adaptive Optics Facility (AOF) is an ESO project started in 2005, which transformed Yepun, one of the four 8m telescopes in Paranal, into an adaptive telescope. This has been done by replacing the conventional secondary mirror of Yepun by a Deformable Secondary Mirror (DSM) and attaching four Laser Guide Star (LGS) Units to its centerpiece. Additionally, two Adaptive Optics (AO) modules (GALACSI serving MUSE a 3D spectrograph, and GRAAL, serving Hawk I a wide field infrared imager) have been assembled onto the telescope Nasmyth adapters, each of them incorporating four LGS WaveFront Sensors (WFS) and one tip-tilt sensor used to control the DSM at 1 kHz frame rate. The complete AOF is installed on Yepun since 2017, has been fully commissioned and delivers science since 2018.

This talk will make a summary of the main drivers of the AOF project, will present the design and performance of the DSM and the 4LGSF, will give some insights about the operation of Yepun together with AOF and will finally illustrate the on-sky performance obtained during the commissioning.

PESSTO, the Public ESO Spectroscopic Survey of Transient Objects (and its successors) has been in operation for almost 10 years. This collaboration brought together a significant fraction of the ESO extra-galactic transient community, with current membership standing at more than 250. During the last decade of operation, PESSTO and other teams have significantly changed the way transient detection, selection and followup is achieved. This has made such observations more efficient, but was also required following the significant increase in transient discovery rate. At the heart of PESSTO operations is the Marshall - this ingests transient detection information and is used to prioritise objects for spectroscopic classification and followup.

In this talk I will briefly discuss the history of supernova detections: from individuals eye-balling photographic plates to community 'brokers' automatically filtering thousands of possible new transients each night. I will then outline the PESSTO collaboration and its operations with specific focus on how the Marshall enables efficient operations, collaboration, and scientific return. I end with an outlook of how transient science will evolve in the next decade with the arrival of the LSST among other surveys.

The study of high-redshift galaxies is key to our global understanding of galaxy formation and evolution. In particular, the interstellar medium (ISM) is a critical component of the complex interplay between the accretion of baryons, the physics that drives the buildup of stars out of this gas, the subsequent chemical evolution and feedback processes, and the reionisation of the Universe. ALMA offers an unprecendented combination of sensitivity, spatial resolution and frequency coverage in the millimetric (mm) and sub-mm domain. Together, these powerful capabilities have transformed our understanding of the (sub)mm extraglactic sky, enabled detailed studies the ISM of the highest-redshift galaxies and redefined our view of the global dust and gas properties of the Universe over large look-back times. These discoveries have in turn both triggered and provided new constraints on theoretical models of galaxy formation and evolution in the early Universe. In this talk, I will highlight some of the ALMA results that have shaped this new era in studies of the cold and distant Universe.

The impact of bars in the evolution of their host galaxies has been studied for over 50 years. Many studies in this field now becoming mature have shown that to fully understand galaxy evolution (including our own Milky Way) it is imperative to understand how bars form and evolve, and in what ways and circumstances they can alter the evolution of the host galaxy. In this hopefully pedagogical talk, I will provide an overview of the current answers to these questions, with theoretical and observational work. This overview will include the effect of environment, the downsizing picture of bar formation, and the connection between bars and bulges and the feeding of AGN.

One of the key aim of the modern astronomy is to understand how galaxies formed and evolved. In this framework, the Milky Way is an excellent testing ground for galaxy formation and evolution theories. The branch of astronomy that studies the history of our Galaxy is the Galactic archaeology. With the advent of large-scale surveys, we are able to produce a detailed mapping of the structural, dynamical chemical, and age distributions of the Milky Way stellar populations. Indeed, combining data from large spectroscopic surveys and Gaia data will allow us to disentangle the full chemo-dynamical history of our Galaxy. In this talk, I will discuss what the Galactic archaeology is, the impact of large-scale surveys on this field and my current work in Galactic archaeology to date stars using chemical clocks.

Scientists generally aim to discover general principles which apply to the phenomena or systems they study. The most general principles, called laws, often require at least one parameter - a constant - in order to relate observations to the theoretical framework. The values of these constants are generally not predicted by any theory but have to be experimentally determined instead. I will speak about how constants relate to our understanding of physics and how fundamental constants can be used to study cosmology, higher-dimensional theories, and constrain dark energy models.

Since the 1st invention of coronagraphy in early 1900 to observe the Sun's corona, recently they have become a key technology for direct imaging of exoplanets. In this talk, I will cover the working of most common coronagraphs, how to quantify them, and factors affecting their performance. I will also talk about coronagraphic results obtained with the NEAR experiment and HCI performance of the 1st gen. ELT instrument METIS.

The Adaptive Optics Facility (AOF) is an upgrade of Yepun (UT4), one of the 8m Unit Telescopes of the Paranal Observatory. The purpose of this project was to turn out Yepun into an Adaptive Telescope, by replacing the classical secondary mirror of the telescope with a Deformable Secondary Mirror (DSM) and by installing 4 Laser Guide Star Units to the mechanical structure of the telescope. In parallel to this development, two Adaptive Optics (AO) modules have been designed and installed on the telescope: GRAAL associated to HAWK-I a wide field IR imager, and GALACSI associated to MUSE a 3D spectrograph working in the visible. The AOF is working at the VLT since end 2016 and is allowing HAWK-I and MUSE to routinely deliver science. ERIS, featuring both an imager and a spectrograph, will be soon commissioned at the Cassegrain focus of Yepun while MAVIS, a large field of view instrument working in the visible, is currently designed and will be installed at the Nasmyth A of Yepun. Both instruments will make an intensive use of the AOF.

Long-baseline optical interferometry, e.g. with the VLTI, enables observations with unprecedented angular resolution. In this talk, I will explain how interferometric techniques can be applied to a single telescope in order to obtain well-calibrated observables and achieve the highest possible angular resolutions of down to ~0.5 λ/D. I will discuss an observational technique called aperture masking interferometry (which we have seen in Peter Tuthill’s KES in 2019) and derive its advancement called kernel phase interferometry. After a brief comparison of these two techniques, I will illustrate how stars and companions look like through the eyes of an interferometer. Finally, I will show how kernel phase interferometry can be used to search for brown dwarf and planetary-mass companions in the nearest star-forming regions.