Clusters in our sample overlaid with considerations for the HLTDS observing fields, as proposed by Rose et al. (2021). Red points indicate clusters for which continuous viewing is not possible due to their ecliptic latitude |β|< 54°. Green points indicate clusters which fulfill this condition, marked by the blue dashed line. The continuous blue line indicates the ecliptic plane. The cluster Abell 1758a is marked orange as a special case, requiring only a minor relaxation of the β constraint (see Sect. 4.3). The Milky Way extinction map is from Schlegel et al. (1998).