2MASS/UKIDSS J − K_S versus K_S CMDs: cl1.5 (top left), cl9.5 (top right), cl16.3 (middle left), cl49.3 (middle right), and cl59.8 (bottom left). Photometry was obtained with a PSF-fitting technique (see text). For each candidate cluster, a diagram of the candidate cluster is shown in the left panel, and that of a control field of equal area in the right panel. Spectroscopically detected early and yellow stars are marked with filled triangles, Miras with squares, RSGs with crosses, and red giants with diamonds; identification numbers are taken from Table 3. In the CMDs of fields cl16.3 and cl49.3, which are rich in RSGs, a continuous curve displays an isochrone of 20 Myr from Lejeune & Schaerer (2001), reddened with A_Ks = 0.50 mag and 0.48 mag, and shifted to DM = 12.93 mag and 14.22 mag, respectively; a dashed line shows the sequence of red clump stars (see Sect. 4.2). The CMD of cl59.8 shows three isochrones from Marigo et al. (2008) with solar metallicity and ages of 100 (dashed line), 200 (continuous line), and 300 Myr (dotted line), which were reddened (A_Ks = 0.55 mag) and shifted to DM = 12.9 mag.