2006BaltA..15..483L

Magnitudes and color indices of 430 stars down to V∼17.5 mag in the eight-color Vilnius + I photometric system were obtained in four areas of diameter 20' within the dark cloud L935 separating the North America and Pelican nebulae. Spectral types, interstellar color excesses, extinctions and distances of stars were determined from the photometric data. The plot of extinction vs. distance shows that the dark cloud begins at a distance of 520±50 pc. About 40 stars in the cloud, mostly K and M dwarfs, are suspected to have Hα emission; these stars also exhibit infrared excesses. Four of them are known pre-main-sequence stars. Our star set contains J205551.3+435225 (V = 13.24) which, according to Cameron and Pasquali (2005), is the O5V type star ionizing the North America and Pelican nebulae. If this spectral type is confirmed, the star would have an extinction A_V between 9 and 10 magnitudes (depending on the accepted extinction law) and a distance which is not very different from the dust cloud distance.