Near-IR photometry of the central exciting cluster of G010.32−00.15. a) J − H versus H − K diagram of the cluster’s stars discussed in the text (photometry from the UKIDSS catalogue). The small red dots correspond to stars located at less than 90″ of the exciting star (#1). The big red dots correspond to the stars identified in Fig. 13, located at less than 10″ from the exciting star. The green plus correspond to O stars, affected by 0 and 18.4 mag of visual extinction. The blue line is the main sequence for B stars and stars of later spectral types. Main sequence stars are expected to lie in the region contained between the two black reddening lines (derived from main sequence O and M0 stars). b) J versus J − K diagram; the red symbols have the same meaning as in Fig. 14a. The two black lines limit the zone occupied by reddened O stars at a distance of 1.75 kpc. The main sequence is also drawn for this distance, and for a visual extinction of 0 mag or 18.4 mag (extinction law of Rieke & Lebofsky 1985).