SIMBAD references

In the area covering the complex of the North America and Pelican nebulae we identified 13 faint stars with J-H and H-K_s color indices which simulate heavily reddened O-type stars. One of these stars is CP05-4 classified as O5V by Comeron and Pasquali (2005). Combining magnitudes of these stars in the passbands I_C, J, H, K_s and [8.3] we were able to suspect that two of them are carbon stars and five are late M-type AGB stars. Interstellar extinction in the direction of these stars was estimated from the background red clump giants in the J-H vs. H-K_s diagram and from star counts in the K_s passband. Four or five stars are found to have a considerable probability of being O-type stars, contributing to the ionization of North America and Pelican. If they really are O-type stars, their interstellar extinction A_V should be from 16 to 35 mag. Two of them seem to be responsible for bright E and J radio rims discovered by Matthews & Goss (1980).