Targeting cluster galaxies for the 4MOST CHANCES Low-

Context. The evolution of galaxies is shaped by both internal processes and their external environments. Galaxy clusters and their surroundings provide ideal laboratories to study these effects, particularly with respect to mechanisms such as quenching and morphological transformation. The Chilean Cluster galaxy Evolution Survey (CHANCES) Low-z sub-survey is part of the CHileAN Cluster galaxy Evolution Survey, a 4MOST community survey designed to uncover the relationship between the formation and evolution of galaxies and hierarchical structure formation as it happens, through deep and wide multi-object spectroscopy. Aims. We present the target selection strategy followed to select galaxy cluster candidate members for the CHANCES Low-z sub-survey. The selection was focussed in and around 50 clusters and two superclusters at z < 0.07, out to (5 × R200) and down to mr = 20.4. Methods. Combining public photometric redshift estimates from the DESI Legacy Imaging Survey and T80S/S-PLUS iDR5 with custom photometric redshifts, we were able to identify likely galaxy cluster candidate members, whose photometric redshifts were consistent with being located at the known redshift of the cluster. We measured the average deviations of their photometric redshifts with respect to the spectroscopic redshift measurements, σNMAD. We tested various selection parameters to maximise completeness, while maintaining purity. Results. We successfully compiled our CHANCES-low-redshift catalogues, split into three different sub-surveys: Low-z bright (mr < 18.5), Low-z faint (18.5 ≤ mr < 20.4), and Low-z faint supplementary. To do so, we selected ≳500 000 galaxy cluster candidate members and included confirmed spectroscopic galaxy cluster members, from which we expect to obtain 4MOST low-resolution (R ∼ 6500) spectra for ∼320 000 galaxies. Conclusions. The CHANCES Low-z target catalogues form a statistically robust sample for spectroscopic follow-up, enabling studies of galaxy evolution and environmental effects in nearby cluster and supercluster environments.