Map of the 50% completeness limits in K_s. Plotted in grayscale is the K_s-band image in logarithmic stretch. Overplotted as contours is the 50% completeness map as derived from the artificial star experiments. The values are indicated with the contour levels. The white contour levels mark the lowest completeness magnitudes: K_s = 15, 16, 17 mag. The 50% completeness ranges from K_s = 19 mag in the southern part of the region to K_s = 15 mag toward W3A, demonstrating a dramatic change in photometric completeness.