This data release presents the first public data products (DR1) from Looking into the faintEst WIth MUSE (LEWIS), an ESO Large Programme investigating extreme low-surface-brightness galaxies in the Hydra I cluster using the Multi Unit Spectroscopic Explorer (MUSE) on the ESO Very Large Telescope. The observations were obtained in service mode between December 2021 and March 2025 under ESO programme 108.222P, PI E. Iodice.

The release includes six fully reduced and flux-calibrated MUSE datacubes and associated white-light images for five ultra-diffuse galaxies in the LEWIS sample. The data cover the wavelength range 4000–9000 Å and were processed using an optimized data-reduction strategy tailored to extremely faint, extended sources, ensuring high-quality sky subtraction and flux calibration. These data products enable spatially resolved studies of stellar kinematics, stellar populations, and globular cluster systems in ultra-diffuse galaxies in a dense cluster environment. The DR1 dataset forms the basis of the first published scientific results of the LEWIS project, with additional data releases planned to include the remaining targets of the survey.

Users can query and download the data via the ESO Archive Science Portal or through programmatic access.
The DOI assigned to this data collection is DOI, and further details are available in the release description.