CMD of all stars within 5′ of the cluster centre, after correction for extinction. Stars highlighted with large dots (orange in the electronic version) are bona fide PMS. The selection of there stars and the physical parameters are discussed later in the paper. Three PMS isochrone (Degl’Innocenti et al. 2008) for ages of 1, 8 and 16 Myr are shown as reference. The ZAMS from Marigo et al. (2008) for solar metallicity and the assumed distance modulus (m − M)₀ = 12.3 is shown by the solid line. The typical uncertainties on magnitudes and colours are indicated by the crosses. The dotted line shows the 50 % completeness limit of the photometry. A reddening vector proportional to E(B − V) = 0.1 (i.e. the typical uncertainty) is also shown.