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Context. The Southern Photometric Local Universe Survey (S-PLUS) is a project to map ~9300 sq deg of the sky using twelve bands (seven narrow and five broadbands). Observations are performed with the T80-South telescope, a robotic telescope located at the Cerro Tololo Observatory in Chile. The survey footprint consists of several large contiguous areas, including fields at high and low galactic latitudes, and towards the Magellanic Clouds. S-PLUS uses fixed exposure times to reach point source depths of about 21 mag in the 𝑔riɀ and 20 mag in theuand the narrow filters. Aims. This paper describes the S-PLUS Data Release 4 (DR4), which includes calibrated images and derived catalogues for over 3000 sq deg, covering the aforementioned area. The catalogues provide multi-band photometry performed with the toolsDoPHOTandSExtractor– point spread function (PSF) and aperture photometry, respectively. In addition to the characterization, we also present the scientific potential of the data. Methods. We use statistical tools to present and compare the photometry obtained through different methods. Overall we find good agreement between the different methods, with a slight systematic offset of 0.05 mag between ourPSFand aperture photometry. We show that the astrometry accuracy is equivalent to that obtained in previous S-PLUS data releases, even in very crowded fields where photometric extraction is challenging. The depths of main survey (MS) photometry for a minimum signal-to-noise ratioS/N= 3 reach from ~19.5 for the bluer bands to ~21.5 mag on the red. The range of magnitudes over which accuratePSFphotometry is obtained is shallower, reaching ~19 to ~20.5 mag depending on the filter. Based on these photometric data, we provide star-galaxy-quasar classification and photometric redshift for millions of objects. Results. We demonstrate the versatility of the data by presenting the results of a project to identify members of four Abell galaxy clusters in the Local Universe. The S-PLUS DR4 data allow for a reliable assessment of cluster membership out to a large radius corresponding to 5 ×r₂₀₀. The S-PLUS DR4 can be accessed through the survey data portal. All the software used to generate the catalogues for this release and the scientific investigation presented is available in the collaboration GitHub repository. Conclusions. The S-PLUS DR4 consists of a large, calibrated public dataset, providing powerful ways for studying Galactic and extra-galactic objects through an extensive set of (broad and narrow) filters. 

Observations of individual massive stars, super-luminous supernovae, gamma-ray bursts, and gravitational wave events involving spectacular black hole mergers indicate that the low-metallicity Universe is fundamentally different from our own Galaxy. Many transient phenomena will remain enigmatic until we achieve a firm understanding of the physics and evolution of massive stars at low metallicity (Z). TheHubbleSpace Telescope has devoted 500 orbits to observing ∼250 massive stars at lowZin the ultraviolet (UV) with the COS and STIS spectrographs under the ULLYSES programme. The complementary X-Shooting ULLYSES (XShootU) project provides an enhanced legacy value with high-quality optical and near-infrared spectra obtained with the wide-wavelength coverage X-shooter spectrograph at ESO’s Very Large Telescope. We present an overview of the XShootU project, showing that combining ULLYSES UV and XShootU optical spectra is critical for the uniform determination of stellar parameters such as effective temperature, surface gravity, luminosity, and abundances, as well as wind properties such as mass-loss rates as a function ofZ. As uncertainties in stellar and wind parameters percolate into many adjacent areas of astrophysics, the data and modelling of the XShootU project is expected to be a game changer for our physical understanding of massive stars at lowZ. To be able to confidently interpretJames WebbSpace Telescope spectra of the first stellar generations, the individual spectra of low-Zstars need to be understood, which is exactly where XShootU can deliver.