Composite 2MASS colour magnitude (J − K_S)/K_S plot for the whole area surrounding RSGC3. Black dots are stars within 7′ of the centre of RSGC3, while blue microdots are stars within 7′ of the centre of Alicante 7. Red squares represent the 16 most likely RSG members of RSGC3, most of which are confirmed spectroscopically. Yellow diamonds as likely RSG members of Alicante 7, as in Fig. 10. Blue triangles are all the stars selected in Field 2 and Field 3 with i > 13.2. The three objects marked with crosses are the three M-type supergiants with high reddening spectroscopically identified in Field 2. Finally, the circles represent all the objects selected in the three fields with i < 13.2, none of which is a reddened supergiant.