2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/901We present new multicolour CCD photometry of the central part of the globular cluster M3, mapping the precise position of ~120 RR Lyrae stars (RRab, RRd, RRc) on the horizontal branch (HB). The location of the double-mode variables (RRd) is in perfect agreement with recent theoretical results. We find a significant internal spread of metallicity amongst the RRab variables.2 pages, 1 figure, ASP Conf. Ser. 2000, vol. 203, pg. 255 - in pressAstrophysicstext