2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/3835I discuss recent seminal work on the LARCS dataset: a panoramic study of rich clusters of galaxies at z~0.12. The importance of observing beyond the cluster core is illustrated by exploiting these data to examine colour gradients across the clusters.2 pages. To appear in ASP Conf Proc `A New Era in Cosmology'. Eds: N. Metcalfe & T. ShanksAstrophysicstext