  Looking into the faintEst WIth MUSE (LEWIS) is an ESO large observing
programme aimed at obtaining the first homogeneous integral-field spectroscopic
survey of 30 extremely low-surface brightness (LSB) galaxies in the Hydra I
cluster of galaxies, with MUSE at ESO-VLT. The majority of LSB galaxies in the
sample (22 in total) are ultra-diffuse galaxies (UDGs). The distribution of
systemic velocities Vsys ranges between 2317 km/s and 5198 km/s and is centred
on the mean velocity of Hydra I (Vsys = 3683 $\pm$ 46 km/s). Considering the
mean velocity and the velocity dispersion of the cluster, 17 out of 20 targets
are confirmed cluster members. To assess the quality of the data and
demonstrate the feasibility of the science goals, we report the preliminary
results obtained for one of the sample galaxies, UDG11. For this target, we
derived the stellar kinematics, including the 2-dimensional maps of
line-of-sight velocity and velocity dispersion, constrained age and
metallicity, and studied the globular cluster (GC) population hosted by the
UDG. Results are compared with the available measurements for UDGs and dwarf
galaxies in literature. By fitting the stacked spectrum inside one effective
radius, we find that UDG11 has a velocity dispersion $\sigma = 20 \pm 8$ km/s,
it is old ($10\pm1$ Gyr), metal-poor ([M/H]=-1.17$\pm$0.11 dex) and has a total
dynamical mass-to-light ratio M$/L_V\sim 14$, comparable to those observed for
classical dwarf galaxies. The spatially resolved stellar kinematics maps
suggest that UDG11 does not show a significant velocity gradient along either
major or minor photometric axes. We find two GCs kinematically associated with
UDG11. The estimated total number of GCs in UDG11, corrected for the
spectroscopic completeness limit, is $N_{GC}= 5.9^{+2.2}_ {-1.8}$, which
corresponds to a GC specific frequency of $S_N = 8.4^{+3.2}_{-2.7}$.
