LEWIS Sample

From the sample of 32 LSB galaxies photometrically detected in the Hydra I cluster (Iodice et al. 2020; La Marca et al. 2022a), we selected 30 objects (22 UDGs and 8 LSB galaxies) for the spectroscopic follow-up with MUSE at ESO-VLT within the LEWIS project. 

They were selected to have an effective surface brightness in the range 25 ≤ μe ≤ 27.5 mag/arcsec² in the g band, which provides the minimum signal-to-noise ratio (S/N ∼ 5–10, depending on the surface brightness) per spaxel in a reasonable integration time (∼2–6 h), which is required for the main goals of this project. 

The two targets excluded from the spectroscopic LEWIS follow-up, UDG14 and UDG19 in La Marca et al. 2022a, are the faintest objects of the photometric sample, with μe = 28.5 mag/arcsec².

Table caption: 

Col. 1: Target name in the LEWIS sample. 

Col. 2 and 3:  RA and DEC coordinates. 

Col. 4 and 5: total r-band magnitude and stellar mass, respectively, derived from the r-band image. 

Col. 6–8: effective surface brightness, central surface brightness, and effective radius in kpc, respectively. Magnitudes and colours are corrected for Galactic extinction using values from Schlegel et al. (1998). 

Col. 9: total number of GCs, which is statistically estimated from photometric data within 1.5Re and corrected for photometric and spatial incompleteness (Iodice et al. 2020; La Marca et al. 2022a). 

Col. 10: status of the observations: C is for observations completed, P is for partial observations, and missing values are galaxies for which the analysis was not successful (see Buttitta et al. 2025 for details). 

Col. 11: total integration time in hours. 

Col. 12: systemic velocity derived by fitting the 1D stacked spectrum inside 1Re.